Composite articles and methods for making the same

ABSTRACT

The present disclosure pertains to composite articles, and in particular a composite face plate for a golf club-head, and methods for making the same. In certain embodiments, a composite face plate for a club-head is formed with a cross-sectional profile having a varying thickness. The face plate comprises a lay-up of multiple, composite prepreg plies. At least a portion of the plies comprise a plurality of elongated prepreg strips arranged in a predetermined criss-cross pattern in the lay-up. The prepreg strips create one or more areas of increased thickness where the strips overlap each other, thereby creating a desired profile for the plate. Metallic or polymer covers or cover layers can be used to define a striking surface.

FIELD

This disclosure pertains generally to composite articles. Moreparticularly, the disclosure pertains to, inter alia, golf clubs andclub-heads that have a composite face insert.

BACKGROUND

With the ever-increasing popularity and competitiveness of golf,substantial effort and resources are currently being expended to improvegolf clubs so that increasingly more golfers can have more enjoyment andmore success at playing golf. Much of this improvement activity has beenin the realms of sophisticated materials and club-head engineering. Forexample, modern “wood-type” golf clubs (notably, “drivers,” “fairwaywoods,” and “utility clubs”), with their sophisticated shafts andnon-wooden club-heads, bear little resemblance to the “wood” drivers,low-loft long-irons, and higher numbered fairway woods used years ago.These modern wood-type clubs are generally called “metal-woods.”

An exemplary metal-wood golf club such as a fairway wood or drivertypically includes a hollow shaft having a lower end to which theclub-head is attached. Most modern versions of these club-heads aremade, at least in part, of a light-weight but strong metal such astitanium alloy. The club-head comprises a body to which a strike plate(also called a face plate) is attached or integrally formed. The strikeplate defines a front surface or strike face that actually contacts thegolf ball.

The current ability to fashion metal-wood club-heads of strong,light-weight metals and other materials has allowed the club-heads to bemade hollow. Use of materials of high strength and high fracturetoughness has also allowed club-head walls to be made thinner, which hasallowed increases in club-head size, compared to earlier club-heads.Larger club-heads tend to provide a larger “sweet spot” on the strikeplate and to have higher club-head inertia, thereby making theclub-heads more “forgiving” than smaller club-heads. Characteristicssuch as size of the sweet spot are determined by many variablesincluding the shape profile, size, and thickness of the strike plate aswell as the location of the center of gravity (CG) of the club-head.

The distribution of mass around the club-head typically is characterizedby parameters such as rotational moment of inertia (MOI) and CGlocation. Club-heads typically have multiple rotational MOIs, eachassociated with a respective Cartesian reference axis (x, y, z) of theclub-head. A rotational MOI is a measure of the club-head's resistanceto angular acceleration (twisting or rotation) about the respectivereference axis. The rotational MOIs are related to, inter alia, thedistribution of mass in the club-head with respect to the respectivereference axes. Each of the rotational MOIs desirably is maximized asmuch as practicable to provide the club-head with more forgiveness.

Another factor in modern club-head design is the face plate. Impact ofthe face plate with the golf ball results in some rearward instantaneousdeflection of the face plate. This deflection and the subsequent recoilof the face plate are expressed as the club-head's coefficient ofrestitution (COR). A thinner face plate deflects more at impact with agolf ball and potentially can impart more energy and thus a higherrebound velocity to the struck ball than a thicker or more rigid faceplate. Because of the importance of this effect, the COR of clubs islimited under United States Golf Association (USGA) rules.

Regarding the total mass of the club-head as the club-head's massbudget, at least some of the mass budget must be dedicated to providingadequate strength and structural support for the club-head. This istermed “structural” mass. Any mass remaining in the budget is called“discretionary” or “performance” mass, which can be distributed withinthe club-head to address performance issues, for example.

Some current approaches to reducing structural mass of a club-head aredirected to making at least a portion of the club-head of an alternativematerial. Whereas the bodies and face plates of most current metal-woodsare made of titanium alloy, several “hybrid” club-heads are availablethat are made, at least in part, of components formed from bothgraphite/epoxy-composite (or another suitable composite material) and ametal alloy. For example, in one group of these hybrid club-heads aportion of the body is made of carbon-fiber (graphite)/epoxy compositeand a titanium alloy is used as the primary face-plate material. Otherclub-heads are made entirely of one or more composite materials.Graphite composites have a density of approximately 1.5 g/cm³, comparedto titanium alloy which has a density of 4.5 g/cm³, which offerstantalizing prospects of providing more discretionary mass in theclub-head.

Composite materials that are useful for making club-head componentscomprise a fiber portion and a resin portion. In general the resinportion serves as a “matrix” in which the fibers are embedded in adefined manner. In a composite for club-heads, the fiber portion isconfigured as multiple fibrous layers or plies that are impregnated withthe resin component. The fibers in each layer have a respectiveorientation, which is typically different from one layer to the next andprecisely controlled. The usual number of layers is substantial, e.g.,fifty or more. During fabrication of the composite material, the layers(each comprising respectively oriented fibers impregnated in uncured orpartially cured resin; each such layer being called a “prepreg” layer)are placed superposedly in a “lay-up” manner. After forming the prepreglay-up, the resin is cured to a rigid condition.

Conventional processes by which fiber-resin composites are fabricatedinto club-head components utilize high (and sometimes constant) pressureand temperature to cure the resin portion in a minimal period of time.The processes desirably yield components that are, or nearly are,“net-shape,” by which is meant that the components as formed have theirdesired final configurations and dimensions. Making a component at ornear net-shape tends to reduce cycle time for making the components andto reduce finishing costs. Unfortunately, at least three main defectsare associated with components made in this conventional fashion: (a)the components exhibit a high incidence of composite porosity (voidsformed by trapped air bubbles or as a result of the released gasesduring a chemical reaction); (b) a relatively high loss of resin occursduring fabrication of the components; and (c) the fiber layers tend tohave “wavy” fibers instead of straight fibers. Whereas some of thesedefects may not cause significant adverse effects on the serviceperformance of the components when the components are subjected tosimple (and static) tension, compression, and/or bending, componentperformance typically will be drastically reduced whenever thesecomponents are subjected to complex loads, such as dynamic andrepetitive loads (i.e., repetitive impact and consequent fatigue).

Manufacturers of metal wood golf club-heads have more recently attemptedto manipulate the performance of their club heads by designing what isgenerically termed a variable face thickness profile for the strikingface. It is known to fabricate a variable-thickness composite strikingplate by first forming a lay-up of prepreg plies, as described above,and then adding additional “partial” layers or plies that are smallerthan the overall size of the plate in the areas where additionalthickness is desired (referred to as the “partial ply” method). Forexample, to form a projection on the rear surface of a composite plate,a series of annular plies, gradually decreasing in size, are added tothe lay-up of prepreg plies.

Unfortunately, variable-thickness composite plates manufactured usingthe partial ply method are susceptible to a high incidence of compositeporosity because air bubbles tend to remain at the edges of the partialplies (within the impact zone of the plate). Moreover, the reinforcingfibers in the prepreg plies are ineffective at their ends. The ends ofthe fibers of the partial plies within the impact zone are stressconcentrations, which can lead to premature delamination and/orcracking. Furthermore, the partial plies can inhibit the steady outwardflow of resin during the curing process, leading to resin-rich regionsin the plate. Resin-rich regions tend to reduce the efficacy of thefiber reinforcement, particularly since the force resulting fromgolf-ball impact is generally transverse to the orientation of thefibers of the fiber reinforcement.

Typically, conventional CNC machining is used during the manufacture ofcomposite face plates, such as for trimming a cured part. Because thetool applies a lateral cutting force to the part (against the peripheraledge of the part), it has been found that such trimming can pull fibersor portions thereof out of their plies and/or induce horizontal crackson the peripheral edge of the part. As can be appreciated, these defectscan cause premature delamination and/or other failure of the part.

While durability limits the application of non-metals in strikingplates, even durable plastics and composites exhibit some additionaldeficiencies. Typical metallic striking plates include a fine groundstriking surface (and for iron-type golf clubs may include a series ofhorizontal grooves) that tends to promote a preferred ball spin in playunder wet conditions. This fine ground surface appears to provide arelief volume for water present at a striking surface/ball impact areaso that impact under wet conditions produces a ball trajectory and shotcharacteristics similar to those obtained under dry conditions. Whilenon-metals suitable for striking plates are durable, these materialsgenerally do not provide a durable roughened, grooved, or texturedstriking surface such as provided by conventional clubs and that isneeded to maintain club performance under various playing conditions.Accordingly, improved striking plates, striking surfaces, and golf clubsthat include such striking plates and surfaces and associated methodsare needed.

SUMMARY

Some disclosed examples pertain to composite articles, and in particulara composite face plate for a golf club-head, and methods for making thesame. In certain embodiments, a composite face plate for a club-head isformed with a cross-sectional profile having a varying thickness. Theface plate comprises a lay-up of multiple, composite prepreg plies. Theface plate can include additional components, such as an outer polymericor metal layer (also referred to as a cap) covering the outer surface ofthe lay-up and forming the striking surface of the face plate. In otherembodiments, the outer surface of the lay-up can be the striking surfacethat contacts a golf ball upon impact with the face plate.

In order to vary the thickness of the lay-up, some of the prepreg pliescomprise elongated strips of prepreg material arranged in a cross-cross,overlapping pattern so as to add thickness to the composite lay-up inone or more regions where the strips overlap each other. The strips ofprepreg plies can be arranged relative to each other in a predeterminedmanner to achieve a desired cross-sectional profile for the face plate.For example, in one embodiment, the strips can be arranged in one ormore clusters having a central region where the strips overlap eachother. The lay-up has a projection or bump formed by the centraloverlapping region of the strips and desirably centered on the sweetspot of the face plate. A relatively thinner peripheral portion of thelay-up surrounds the projection. In another embodiment, the lay-up caninclude strips of prepreg plies that are arranged to form an annularprojection surrounding a relatively thinner central region of the faceplate, thereby forming a cross-sectional profile that is reminiscent ofa “volcano.”

The strips of prepreg material desirably extend continuously across thefinished composite part; that is, the ends of the strips are at theperipheral edge of the finished composite part. In this manner, thelongitudinally extending reinforcing fibers of the strips also extendcontinuously across the finished composite part such that the ends ofthe fibers are at the periphery of the part. In addition, the lay-up caninitially be formed as an “oversized” part in which the reinforcingfibers of the prepreg material extend into a peripheral sacrificialportion of the lay-up. Consequently, the curing process for the lay-upcan be controlled to shift defects into the sacrificial portion of thelay-up, which subsequently can be removed to provide a finished partwith little or no defects. Moreover, the durability of the finished partis increased because the free ends of the fibers are at the periphery ofthe finished part, away from the impact zone.

The sacrificial portion desirably is trimmed from the lay-up usingwater-jet cutting. In water-jet cutting, the cutting force is applied ina direction perpendicular to the prepreg plies (in a direction normal tothe front and rear surfaces of the lay-up), which minimizes damage tothe reinforcing fibers.

In one representative embodiment, a golf club-head comprises a bodyhaving a crown, a heel, a toe, and a sole, and defining a front opening.The head also includes a variable-thickness face insert closing thefront opening of the body. The insert comprises a lay-up of multiple,composite prepreg plies, wherein at least a portion of the pliescomprise a plurality of elongated prepreg strips arranged in acriss-cross pattern defining an overlapping region where the stripsoverlap each other. The lay-up has a first thickness at a locationspaced from the overlapping region and a second thickness at theoverlapping region, the second thickness being greater than the firstthickness.

In another representative embodiment, a golf club-head comprises a bodyhaving a crown, a heel, a toe, and a sole, and defining a front opening.The head also includes a variable-thickness face insert closing thefront opening of the body. The insert comprises a lay-up of multiple,composite prepreg plies, the lay-up having a front surface, a peripheraledge surrounding the front surface, and a width. At least a portion ofthe plies comprise elongated strips that are narrower than the width ofthe lay-up and extend continuously across the front surface. The stripsare arranged within the lay-up so as to define a cross-sectional profilehaving a varying thickness.

In another representative embodiment, a composite face plate for aclub-head of a golf club comprises a composite lay-up comprisingmultiple prepreg layers, each prepreg layer comprising at least oneresin-impregnated layer of longitudinally extending fibers at arespective orientation. The lay-up has an outer peripheral edge definingan overall size and shape of the lay-up. At least a portion of thelayers comprise a plurality of composite panels, each panel comprising aset of one or more prepreg layers, each prepreg layer in the panelshaving a size and shape that is the same as the overall size and shapeof the lay-up. Another portion of the layers comprise a plurality ofsets of elongated strips, the sets of strips being interspersed betweenthe panels within the lay-up. The strips extend continuously fromrespective first locations on the peripheral edge to respective secondlocations on the peripheral edge and define one or more areas ofincreased thickness of the lay-up where the strips overlap within thelay-up.

In another representative embodiment, a method for making a compositeface plate for a club-head of a golf club comprises forming a lay-up ofmultiple prepreg composite plies, a portion of the plies comprisingelongated strips arranged in a criss-cross pattern defining one or moreareas of increased thickness in the lay-up where one or more of thestrips overlap each other. The method can further include at leastpartially curing the lay-up, and shaping the at least partially curedlay-up to form a part having specified dimensions and shape for use as aface plate or part of a face plate for a club-head.

In still another representative embodiment, a method for making acomposite face plate for a club-head of a golf club comprises forming alay-up of multiple prepreg plies, each prepreg ply comprising at leastone layer of reinforcing fibers impregnated with a resin. The method canfurther include at least partially curing the lay-up, and water-jetcutting the at least partially cured lay-up to form a composite parthaving specified dimensions and shape for use as a face plate or part ofa face plate in a club-head.

In some examples, golf club heads comprise a club body and a strikingplate secured to the club body. The striking plate includes a face plateand a cover plate secured to the face plate and defining a strikingsurface, wherein the striking surface includes a plurality of scorelineindentations. In some examples, an adhesive layer secures the coverplate to the face plate. In other alternative embodiments, the scorelineindentations are at least partially filled with a pigment selected tocontrast with an appearance of an impact area of the striking surfaceand the cover plate is metallic and has a thickness between about 0.25mm and 0.35 mm. In further examples, the scoreline indentations arebetween about 0.05 and 0.09 mm deep. In other representative examples, aratio of a scoreline indentation width to a cover plate thickness isbetween about 2.5 and 3.5, and the face plate is formed of a titaniumalloy. In some examples, the scoreline indentations include transitionregions having radii of between about 0.2 mm and 0.6 mm, and the coverplate includes a rim configured to extend around a perimeter of the faceplate. According to some embodiments, the face plate is a composite faceplate and the club body is a wood-type club body.

Cover plates for a golf club face plate comprise a titanium alloy sheethaving bulge and roll curvatures, and including a plurality of scorelineindentations. A scoreline indentation depth D is between about 0.05 mmand 0.12 mm, and a titanium alloy sheet thickness T is between about0.20 mm and 0.40 mm.

In further examples, golf club heads comprise a club body and a strikingplate secured to the club body. The striking plate includes a metalliccover having a plurality of impact resistant scoreline indentationssituated on a striking surface. In some examples, the metallic cover isbetween about 0.2 mm and 1.0 mm thick and the scoreline indentationshave depths between about 0.1 mm and 0.02 mm. In further examples, thescoreline indentations have a depth D and the metallic cover has athickness T such that a ratio D/T is between about 0.15 and 0.30 orbetween about 0.20 and 0.25. In additional examples, the face plate is avariable thickness face plate.

Methods comprise selecting a metallic cover sheet and trimming themetallic cover sheet so as to conform to a golf club face plate. Themetallic cover sheet provides a striking surface for a golf club. Aplurality of scoreline indentations are defined in the striking surface,wherein the metallic cover sheet has a thickness T between about 0.1 mmand 0.5 mm, and the scoreline indentations have a depth D such that aratio D/T is between about 0.1 and 0.4. In additional examples, a rim isformed on the cover sheet and is configured to cover a perimeter of theface plate. In typical examples, the metallic sheet is a titanium alloysheet and is trimmed after formation of the scoreline indentations. Insome examples, the scoreline indentations are formed in an impact areaof the striking surface or outside of an impact area of the strikingsurface.

According to some examples, golf club heads (wood-type or iron-type)comprise a club body and a striking plate secured to the club body. Thestriking plate includes a composite face plate having a front surfaceand a polymer cover layer secured to the front surface of the faceplate, the polymer cover layer having a textured striking surface. Insome embodiments, a thickness of the cover layer is between about 0.1 mmand about 2.0 mm or about 0.2 mm and 1.2 mm, or the thickness of thecover layer is about 0.4 mm. In further examples, the striking face ofthe composite face plate has an effective Shore D hardness of at leastabout 75, 80, or 85. In additional representative examples, the texturedstriking surface has one or more of a mean surface roughness betweenabout 1 μm and 10 μm, a mean surface feature frequency of at least about2/mm, or a surface profile kurtosis greater than about 1.5, 1.75, or2.0. In additional embodiments, the textured striking surface has a meansurface roughness of less than about 4.5 μm, a mean surface featurefrequency of at least about 3/mm, and a surface profile kurtosis greaterthan about 2 as measured in a top-to-bottom direction, a toe-to-heeldirection, or along both directions. In some examples, the strikingsurface is textured along a top-to-bottom direction or a toe-to-heeldirection only. In other examples, the striking surface is texturedalong an axis that is tilted with respect to a toe-to-heel and atop-to-bottom direction.

Methods comprise providing a face plate for a golf club and a coverlayer for a front surface of the face plate. A striking surface of thecover layer is patterned so as to provide a roughened or texturedstriking surface. According to some examples, the roughened strikingsurface is patterned to include a periodic array of surface featuresthat provide a mean roughness less than about 5 μm and a mean surfacefeature frequency along at least one axis substantially parallel to thestriking surface of at least 2/mm. In other examples, the strikingsurface of the cover layer is patterned with a mold. In furtherexamples, the striking surface is patterned by pressing a fabric againstthe cover layer, and subsequently removing the fabric. In arepresentative example, the cover layer is formed of a thermoplastic andthe fabric is applied as the cover layer is formed.

Golf club heads comprise a face plate having a front surface and acontrol layer situated on the front surface of the face plate, whereinthe control layer has a striking surface having a surface roughnessconfigured to provide a ball spin of about 2500 rpm, 3000 rpm, or 3500rpm under wet conditions. In some examples, the control layer is apolymer layer. In further examples, the control layer is a polymer layerhaving a thickness of between about 0.3 mm and 0.5 mm, and the surfaceroughness of the striking surface is substantially periodic along atleast one axis that is substantially parallel to the striking surface.In a representative examples, the striking surface of the face plate hasa Shore D hardness of at least about 75, 80, or more preferably, atleast about 85. The polymer layer can be a thermoset or thermoplasticmaterial. In representative examples, the polymer layer is a SURLYNionomer or similar material, or a urethane, preferably a non-yellowingurethane.

The foregoing and other objects, features, and advantages of theinvention will become more apparent from the following detaileddescription, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a “metal-wood” club-head, showingcertain general features pertinent to the instant disclosure.

FIG. 2 is a front elevation view of one embodiment of a net-shapecomposite component used to form the strike plate of a club-head, suchas the club-head shown in FIG. 1.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 2.

FIG. 5 is an exploded view of one embodiment of a composite lay-up fromwhich the component shown in FIG. 2 can be formed.

FIG. 6 is an exploded view of a group of prepreg plies of differingfiber orientations that are stacked to form a “quasi-isotropic”composite panel that can be used in the lay-up illustrated in FIG. 5.

FIG. 7 is a plan view of a group or cluster of elongated prepreg stripsthat can be used in the lay-up illustrated in FIG. 5.

FIG. 8A-8C are plan views illustrating the manner in which clusters ofprepreg strips can be oriented at different rotational positionsrelative to each other in a composite lay-up to create an angular offsetbetween the strips of adjacent clusters.

FIG. 9 is a top plan view of the composite lay-up shown in FIG. 5.

FIGS. 10A-10C are plots of temperature, viscosity, and pressure,respectively, versus time in a representative embodiment of a processfor forming composite components.

FIGS. 11A-11C are plots of temperature, viscosity, and pressure,respectively, versus time in a representative embodiment of a process inwhich each of these variables can be within a specified respective range(hatched areas).

FIG. 12 is a plan view of a simplified lay-up of composite plies fromwhich the component shown in FIG. 2 can be formed.

FIG. 13 is a front elevation view of another net-shape compositecomponent that can be used to form the strike plate of a club-head.

FIG. 14 is a cross-sectional view taken along line 14-14 of FIG. 13.

FIG. 15 is a cross-sectional view taken along line 15-15 of FIG. 13.

FIG. 16 is a top plan view of one embodiment of a lay-up of compositeplies from which the component shown in FIG. 13 can be formed.

FIG. 17 is an exploded view of the first few groups of composite pliesthat are used to form the lay-up shown in FIG. 16.

FIG. 18 is a partial sectional view of the upper lip region of anembodiment of a club-head of which the face plate comprises a compositeplate and a metal cap.

FIG. 19 is a partial sectional view of the upper lip region of anembodiment of a club-head of which the face plate comprises a compositeplate and a polymeric outer layer.

FIGS. 20-23 illustrate a metallic cover for a composite face plate.

FIG. 24 is a side perspective view of a wood-type golf club head.

FIG. 25 is a front perspective view of a wood-type golf club head.

FIG. 26 is a top perspective view of a wood-type golf club head.

FIG. 27 is a back perspective view of a wood-type golf club head.

FIG. 28 is a front perspective view of a wood-type golf club headshowing a golf club head center of gravity coordinate system.

FIG. 29 is a top perspective view of a wood-type golf club head showinga golf club head center of gravity coordinate system.

FIG. 30 is a front perspective view of a wood-type golf club headshowing a golf club head origin coordinate system.

FIG. 31 is a top perspective view of a wood-type golf club head showinga golf club head origin coordinate system.

FIGS. 32-34 illustrate a striking plate that includes a face plate and acover layer having a striking surface with a patterned roughness.

FIG. 35 illustrates attachment of a striking plate comprising a faceplate and a cover layer to a club body.

FIGS. 36-37 illustrate a representative striking plate that includes acover layer having a roughened striking surface.

FIGS. 38-39 illustrate a representative striking plate that includes acover layer having a roughened striking surface.

FIGS. 40-42 illustrate another representative striking plate thatincludes a cover layer having a roughened striking surface.

FIGS. 43-44 are surface profiles of a representative textured strikingsurface of polymer layer produced with a peel ply fabric.

FIG. 45 is a photograph of a portion of a peel ply fabric texturedsurface.

FIGS. 46-48 illustrate another representative striking plate thatincludes a cover layer having a roughened striking surface.

FIG. 49 is a surface profile of the roughened surface of FIGS. 46-48.

DETAILED DESCRIPTION

This disclosure is set forth in the context of representativeembodiments that are not intended to be limiting in any way.

In the following description, certain terms may be used such as “up,”“down,”, “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,”and the like. These terms are used, where applicable, to provide someclarity of description when dealing with relative relationships. But,these terms are not intended to imply absolute relationships, positions,and/or orientations. For example, with respect to an object, an “upper”surface can become a “lower” surface simply by turning the object over.Nevertheless, it is still the same object.

As used herein, the singular forms “a,” “an,” and “the” refer to one ormore than one, unless the context clearly dictates otherwise.

As used herein, the term “includes” means “comprises.” For example, adevice that includes or comprises A and B contains A and B but mayoptionally contain C or other components other than A and B. A devicethat includes or comprises A or B may contain A or B or A and B, andoptionally one or more other components such as C.

As used herein, the term “composite” or “composite materials” means afiber-reinforced polymeric material.

The main features of an exemplary hollow “metal-wood” club-head 10 aredepicted in FIG. 1. The club-head 10 comprises a face plate, strikeplate, or striking plate 12 and a body 14. The face plate 12 typicallyis convex, and has an external (“striking”) surface (face) 13. The body14 defines a front opening 16. A face support 18 is disposed about thefront opening 16 for positioning and holding the face plate 12 to thebody 14. The body 14 also has a heel 20, a toe 22, a sole 24, a top orcrown 26, and a hosel 28. Around the front opening 16 is a “transitionzone” 15 that extends along the respective forward edges of the heel 20,the toe 22, the sole 24, and the crown 26. The transition zone 15effectively is a transition from the body 14 to the face plate 12. Theface support 18 can comprise a lip or rim that extends around the frontopening 16 and is released relative to the transition zone 15 as shown.The hosel 28 defines an opening 30 that receives a distal end of a shaft(not shown). The opening 16 receives the face plate 12, which rests uponand is bonded to the face support 18 and transition zone 15, therebyenclosing the front opening 16. The transition zone 15 can include asole-lip region 18 d, a crown-lip region 18 a, a heel-lip region 18 c,and a toe-lip region 18 b. These portions can be contiguous, as shown,or can be discontinuous, with spaces between them.

In a club-head according to one embodiment, at least a portion of theface plate 12 is made of a composite including multiple plies or layersof a fibrous material (e.g., graphite, or carbon, fiber) embedded in acured resin (e.g., epoxy). For example, the face plate 12 can comprise acomposite component (e.g., component 40 shown in FIGS. 2-4) that has anouter polymeric layer forming the striking surface 13. Examples ofsuitable polymers that can be used to form the outer coating, or cap,are described in detail below. Alternatively, the face plate 12 can havean outer metallic cap forming the external striking surface 13 of theface plate, as described in U.S. Pat. No. 7,267,620, which isincorporated herein by reference.

An exemplary thickness range of the composite portion of the face plateis 7.0 mm or less. The composite desirably is configured to have arelatively consistent distribution of reinforcement fibers across across-section of its thickness to facilitate efficient distribution ofimpact forces and overall durability. In addition, the thickness of theface plate 12 can be varied in certain areas to achieve differentperformance characteristics and/or improve the durability of theclub-head. The face plate 12 can be formed with any of variouscross-sectional profiles, depending on the club-head's desireddurability and overall performance, by selectively placing multiplestrips of composite material in a predetermined manner in a compositelay-up to form a desired profile.

Attaching the face plate 12 to the support 18 of the club-head body 14may be achieved using an appropriate adhesive (typically an epoxyadhesive or a film adhesive). To prevent peel and delamination failureat the junction of an all-composite face plate with the body of theclub-head, the composite face plate can be recessed from or can besubstantially flush with the plane of the forward surface of the metalbody at the junction. Desirably, the face plate is sufficiently recessedso that the ends of the reinforcing fibers in the composite componentare not exposed.

The composite portion of the face plate is made as a lay-up of multipleprepreg plies. For the plies the fiber reinforcement and resin areselected in view of the club-head's desired durability and overallperformance. In order to vary the thickness of the lay-up, some of theprepreg plies comprise elongated strips of prepreg material arranged inone or more sets of strips. The strips in each set are arranged in across-cross, overlapping pattern so as to add thickness to the compositelay-up in the region where the strips overlap each other, as furtherdescribed in greater detail below. The strips desirably extendcontinuously across the finished composite part; that is, the ends ofthe strips are at the peripheral edge of the finished composite part. Inthis manner, the longitudinally extending reinforcing fibers of thestrips also can extend continuously across the finished composite partsuch that the ends of the fibers are at the periphery of the part.Consequently, during the curing process, defects can be shifted toward aperipheral sacrificial portion of the composite lay-up, whichsacrificial portion subsequently can be removed to provide a finishedpart with little or no defects. Moreover, the durability of the finishedpart is increased because the free ends of the fibers are at theperiphery of the finished part, away from the impact zone.

In tests involving certain club-head configurations, composite portionsformed of prepreg plies having a relatively low fiber areal weight (FAW)have been found to provide superior attributes in several areas, such asimpact resistance, durability, and overall club performance. (FAW is theweight of the fiber portion of a given quantity of prepreg, in units ofg/m².) FAW values below 100 g/m², and more desirably below 70 g/m², canbe particularly effective. A particularly suitable fibrous material foruse in making prepreg plies is carbon fiber, as noted. More than onefibrous material can be used. In other embodiments, however, prepregplies having FAW values above 100 g/m² may be used.

In particular embodiments, multiple low-FAW prepreg plies can be stackedand still have a relatively uniform distribution of fiber across thethickness of the stacked plies. In contrast, at comparable resin-content(R/C, in units of percent) levels, stacked plies of prepreg materialshaving a higher FAW tend to have more significant resin-rich regions,particularly at the interfaces of adjacent plies, than stacked plies oflow-FAW materials. Resin-rich regions tend to reduce the efficacy of thefiber reinforcement, particularly since the force resulting fromgolf-ball impact is generally transverse to the orientation of thefibers of the fiber reinforcement.

FIGS. 2-4 show an exemplary embodiment of a finished component 40 thatis fabricated from a plurality of prepreg plies or layers and has adesired shape and size for use as a face plate for a club-head or aspart of a face plate for a clubhead. The composite part 40 has a frontsurface 42 and a rear surface 44. In this example the composite part hasan overall convex shape, a central region 46 of increased thickness, anda peripheral region 48 having a relatively reduced thickness extendingaround the central region. The central region 46 in the illustratedexample is in the form of a projection or cone on the rear surfacehaving its thickest portion at a central point 50 (FIG. 3) and graduallytapering away from the point in all directions toward the peripheralregion 48. The central point 50 represents the approximate center of the“sweet spot” (optimal strike zone) of the face plate 12, but notnecessarily the geometric center of the face plate. The thicker centralregion 46 adds rigidity to the central area of the face plate 12, whicheffectively provides a more consistent deflection across the face plate.In certain embodiments, the central region 46 has a thickness of about 5mm to about 7 mm and the peripheral region 48 has a thickness of about 4mm to about 5 mm.

In certain embodiments, the composite component 40 is fabricated byfirst forming an oversized lay-up of multiple prepreg plies, and thenmachining a sacrificial portion from the cured lay-up to form thefinished part 40. FIG. 9 is a top plan view of one example of a lay-up38 from which the composite component 40 can be formed. The line 64 inFIG. 9 represents the outline of the component 40. Once cured, theportion surrounding the line 64 can be removed to form the component 40.FIG. 5 is an exploded view of the lay-up 38. In the lay-up, each prepregply desirably has a prescribed fiber orientation, and the plies arestacked in a prescribed order with respect to fiber orientation.

As shown in FIG. 5, the illustrated lay-up 38 is comprised of aplurality of sets, or unit-groups, 52 a-52 k of one or more prepregplies of substantially uniform thickness and one or more sets, orunit-groups, 54 a-54 g of individual plies in the form of elongatedstrips 56. For purposes of description, each set 52 a-52 k of one ormore plies can be referred to as a composite “panel” and each set 54a-54 g can be referred to as a “cluster” of elongated strips. Theclusters 54 a-54 g of elongated strips 56 are interposed between thepanels 52 a-52 k and serve to increase the thickness of the finishedpart 40 at its central region 46 (FIG. 2). Each panel 52 a-52 kcomprises one or more individual prepreg plies having a desired fiberorientation. The individual plies forming each panel 52 a-52 k desirablyare of sufficient size and shape to form a cured lay-up from which thesmaller finished component 40 can be formed substantially free ofdefects. The clusters 54 a-54 g of strips 56 desirably are individuallypositioned between and sandwiched by two adjacent panels (i.e., thepanels 52 a-52 k separate the clusters 54 a-54 g of strips from eachother) to facilitate adhesion between the many layers of prepregmaterial and provide an efficient distribution of fibers across across-section of the part.

In particular embodiments, the number of panels 52 a-52 k can range from9 to 14 (with eleven panels 52 a-52 k being used in the illustratedembodiment) and the number of clusters 54 a-54 g can range from 1 to 12(with seven clusters 54 a-54 g being used in the illustratedembodiment). However, in alternative embodiments, the number of panelsand clusters can be varied depending on the desired profile andthickness of the part.

The prepreg plies used to form the panels 52 a-52 k and the clusters 54a-54 g desirably comprise carbon fibers impregnated with a suitableresin, such as epoxy. An example carbon fiber is “34-700” carbon fiber(available from Grafil, Sacramento, Calif.), having a tensile modulus of234 Gpa (34 Msi) and a tensile strength of 4500 Mpa (650 Ksi). AnotherGrafil fiber that can be used is “TR50S” carbon fiber, which has atensile modulus of 240 Gpa (35 Msi) and a tensile strength of 4900 Mpa(710 ksi). Suitable epoxy resins are types “301” and “350” (availablefrom Newport Adhesives and Composites, Irvine, Calif.). An exemplaryresin content (R/C) is 40%.

FIG. 6 is an exploded view of the first panel 52 a. For convenience ofreference, the fiber orientation (indicated by lines 66) of each ply ismeasured from a horizontal axis of the club-head's face plane to a linethat is substantially parallel with the fibers in the ply. As shown inFIG. 6, the panel 52 a in the illustrated example comprises a first ply58 a having fibers oriented at +45 degrees, a second ply 58 b havingfibers oriented at 0 degrees, a third ply 58 c having fibers oriented at−45 degrees, and a fourth ply 58 d having fibers oriented at 90 degrees.The panel 52 a of plies 58 a-58 d thus form a “quasi-isotropic” panel ofprepreg material. The remaining panels 52 b-52 k can have the samenumber of prepreg plies and fiber orientation as set 52 a.

The lay-up illustrated in FIG. 5 can further include an “outermost”fiberglass ply 70 adjacent the first panel 52 a, a single carbon-fiberply 72 adjacent the eleventh and last panel 52 k, and an “innermost”fiberglass ply 74 adjacent the single ply 72. The single ply can have afiber orientation of 90 degrees as shown. The fiberglass plies 70, 74can have fibers oriented at 0 degrees and 90 degrees. The fiberglassplies 70, 74 are essentially provided as sacrificial layers that protectthe carbon-fiber plies when the cured lay-up is subjected to surfacefinishing such as sand blasting to smooth the outer surfaces of thepart.

FIG. 7 is an enlarged plan view of the first cluster 54 a of elongatedprepreg strips which are arranged with respect to each other so that thecluster has a variable thickness. The cluster 54 a in the illustratedexample includes a first strip 56 a, a second strip 56 b, a third strip56 c, a fourth strip 56 d, a fifth strip 56 e, a sixth strip 56 f, and aseventh strip 56 g. The strips are stacked in a criss-cross pattern suchthat the strips overlap each other to define an overlapping region 60and the ends of each strip are angularly spaced from adjacent ends ofanother strip. The cluster 54 a is therefore thicker at the overlappingregion 60 than it is at the ends of the strips. The strips can have thesame or different lengths and widths, which can be varied depending onthe desired overall shape of the composite part 40, although each stripdesirably is long enough to extend continuously across the finished part40 that is cut or otherwise machined from the oversized lay-up.

The strips 56 a-56 g in the illustrated embodiment are of equal lengthand are arranged such that the geometric center point 62 of the clustercorresponds to the center of each strip. The first three strips 56 a-56c in this example have a width w₁ that is greater than the width w₂ ofthe last four strips 56 d-56 g. The strips define an angle α between the“horizontal” edges of the second strip 56 b and the adjacent edges ofstrips 56 a and 56 c, an angle μ between the edges of strip 56 b and theclosest edges of strips 56 d and 56 g, and an angle θ between the edgesof strip 56 b and the closest edges of strips 56 e and 56 f. In aworking embodiment, the width w₁ is about 20 mm, the width w₂ is about15 mm, the angle α is about 24 degrees, the angle μ is about 54 degrees,and the angle θ is about 78 degrees.

Referring again to FIG. 5, each cluster 54 a-54 g desirably is rotatedslightly or angularly offset with respect to an adjacent cluster so thatthe end portions of each strip in a cluster are not aligned with the endportions of the strips of an adjacent cluster. In this manner, theclusters can be arranged relative to each other in the lay-up to providea substantially uniform thickness in the peripheral region 48 of thecomposite part (FIG. 3). In the illustrated embodiment, for example, thefirst cluster 54 a has an orientation of −18 degrees, meaning that the“upper” edge of the second strip 56 b extends at a −18 degree angle withrespect to the “upper” horizontal edge of the adjacent unit-group 52 c(as best shown in FIG. 8A). The next successive cluster 54 b has anorientation of 0 degrees, meaning that the second strip 56 b is parallelto the “upper” horizontal edge of the adjacent unit-group 52 d (as bestshown in FIG. 8B). The next successive cluster 54 c has an orientationof +18 degrees, meaning that the “lower” edge of the respective secondstrip 56 b of cluster 54 c extends at a +18 degree angle with respect tothe “lower” edge of the adjacent unit-group 52 e. Clusters 54 d, 54 e,54 f, and 54 g (FIG. 5) can have an orientation of 0 degrees, −18degrees, 0 degrees, and +18 degrees, respectively.

When stacked in the lay-up, the overlapping regions 60 of the clustersare aligned in the direction of the thickness of the lay-up to increasethe thickness of the central region 46 of the part 40 (FIG. 3), whilethe “spokes” (the strips 56 a-56 g) are “fanned” or angularly spacedfrom each other within each cluster and with respect to spokes inadjacent clusters. Prior to curing/molding, the lay-up has across-sectional profile that is similar to the finished part 40 (FIGS.2-4) except that the lay-up is flat, that is, the lay-up does not havean overall convex shape. Thus, in profile, the rear surface of thelay-up has a central region of increased thickness and gradually tapersto a relatively thinner peripheral region of substantially uniformthickness surrounding the central region. In a working embodiment, thelay-up has a thickness of about 5 mm at the center of the central regionand a thickness of about 3 mm at the peripheral region. A greater orfewer number of panels and/or clusters of strips can be used to vary thethickness at the central region and/or peripheral region of the lay-up.

To form the lay-up, according to one specific approach, formation of thepanels 52 a-52 k may be done first by stacking individual precut,prepreg plies 58 a-58 d of each panel. After the panels are formed, thelay-up is built up by laying the second panel 52 b on top of the firstpanel 52 a, and then forming the first cluster 54 a on top of the secondpanel 52 b by laying individual strips 56 a-56 g in the prescribedmanner. The remaining panels 52 c-52 k and clusters 54 b-54 g are thenadded to the lay-up in the sequence shown in FIG. 5, followed by thesingle ply 72. The fiberglass plies 70, 74 can then be added to thefront and back of the lay-up.

The fully-formed lay-up can then be subjected to a “debulking” orcompaction step (e.g., using a vacuum table) to remove and/or reduce airtrapped between plies. The lay-up can then be cured in a mold that isshaped to provide the desired bulge and roll of the face plate. Anexemplary curing process is described in detail below. Alternatively,any desired bulge and roll of the face plate may be formed during one ormore debulking or compaction steps performed prior to curing. To formthe bulge or roll, the debulking step can be performed against a diepanel having the final desired bulge and roll. In either case, followingcuring, the cured lay-up is removed from the mold and machined to formthe part 40.

The following aspects desirably are controlled to provide compositecomponents that are capable of withstanding impacts and fatigue loadingsnormally encountered by a club-head, especially by the face plate of theclub-head. These three aspects are: (a) adequate resin content; (b)fiber straightness; and (c) very low porosity in the finished composite.These aspects can be controlled by controlling the flow of resin duringcuring, particularly in a manner that minimizes entrapment of air in andbetween the prepreg layers. Air entrapment is difficult to avoid duringlaying up of prepreg layers. However, air entrapment can besubstantially minimized by, according to various embodiments disclosedherein, imparting a slow, steady flow of resin for a defined length oftime during the laying-up to purge away at least most of the air thatotherwise would become occluded in the lay-up. The resin flow should besufficiently slow and steady to retain an adequate amount of resin ineach layer for adequate inter-layer bonding while preserving therespective orientations of the fibers (at different respective angles)in the layers. Slow and steady resin flow also allows the fibers in eachply to remain straight at their respective orientations, therebypreventing the “wavy fiber” phenomenon. Generally, a wavy fiber has anorientation that varies significantly from its naturally projecteddirection.

As noted above, the prepreg strips 56 desirably are of sufficient lengthsuch that the fibers in the strips extend continuously across the part40; that is, the ends of each fiber are located at respective locationson the outer peripheral edge 49 of the part 40 (FIGS. 2-4). Similarly,the fibers in the prepreg panels 52 a-52 k desirably extend continuouslyacross the part between respective locations on the outer peripheraledge 49 of the part. During curing, air bubbles tend to flow along thelength of the fibers toward the outer peripheral (sacrificial) portionof the lay-up. By making the strips sufficiently long and the panelslarger than the final dimensions of the part 40, the curing process canbe controlled to remove substantially all of the entrapped air bubblesfrom the portion of the lay-up that forms the part 40. The peripheralportion of the lay-up is also where wavy fibers are likely to be formed.Following curing, the peripheral portion of the lay-up is removed toprovide a net-shape part (or near net-shape part if further finishingsteps are performed) that has a very low porosity as well as straightfibers in each layer of prepreg material.

In working examples, parts have been made without any voids, orentrapped air, and with a single void in one of the prepreg plies of thelay-up (either a strip or a panel-size ply). Parts in which there is asingle void having its largest dimension equal to the thickness of a ply(about 0.1 mm) have a void content, or porosity, of about 1.7×10⁻⁶percent or less by volume.

FIGS. 10A-10C depict an embodiment of a process (pressure andtemperature as functions of time) in which slow and steady resin flow isperformed with minimal resin loss. FIG. 10A shows temperature of thelay-up as a function of time. The lay-up temperature is substantiallythe same as the tool temperature. The tool is maintained at an initialtool temperature T_(i), and the uncured prepreg lay-up is placed orformed in the tool at an initial pressure P₁ (typically atmosphericpressure). The tool and uncured prepreg is then placed in a hot-press ata tool-set temperature T_(s), resulting in an increase in the tooltemperature (and thus the lay-up temperature) until the tool temperatureeventually reaches equilibrium with the set temperature T_(s) of thehot-press. As the temperature of the tool increases from T_(i) to T_(s),the hot-press pressure is kept at P₁ for t=0 to t=t₁. At t=t₁, thehot-press pressure is ramped from P₁ to P₂ such that, at t=t₂, P=P₂.Between T_(i) and T_(s), the temperature increase of the tool and lay-upis continuous. Exemplary rates of change of temperature and pressureare: ΔT ˜30-60° C./minute up to t₁, and ΔP ˜50 psi/minute from t₁ to t₂.

As the tool temperature increases from T_(i) to T_(s), the viscosity ofthe resin first decreases to a minimum, at time t₁, before the viscosityrises again due to cross-linking of the resin (FIG. 10B). At time t₁,resin flows relatively easily. This increased flow poses an increasedrisk of resin loss, especially if the pressure in the tool is elevated.Elevated tool pressure at this stage also causes other undesirableeffects such as a more agitated flow of resin. Hence, tool pressureshould be maintained relatively low at and around t₁ (see FIG. 10C).After t₁, cross-linking of the resin begins and progresses, causing aprogressive rise in resin viscosity (FIG. 10B), so tool pressuredesirably is gradually increased in the time span from t₁ to t₂ to allow(and to encourage) adequate and continued (but nevertheless controlled)resin flow. The rate at which pressure is increased should be sufficientto reach maximum pressure P₂ slightly before the end of rapid increasein resin viscosity. Again, a desired rate of change is ΔP˜50 psi/minutefrom t₁ to t₂. At time t₂ the resin viscosity desirably is approximately80% of maximum.

Curing continues after time t₂ and follows a schedule of relativelyconstant temperature T_(s) and constant pressure P₂. Note that resinviscosity exhibits some continued increase (typically to approximately90% of maximum) during this phase of curing. This curing (also called“pre-cure”) ends at time t₃ at which the component is deemed to havesufficient rigidity (approximately 90% of maximum) and strength forhandling and removal from the tool, although the resin may not yet havereached a “full-cure” state (at which the resin exhibits maximumviscosity). A post-processing step typically follows, in which thecomponents reach a “full cure” in a batch heating mode or other suitablemanner.

Thus, important parameters of this specific process are: (a) T_(s), thetool-set temperature (or typical resin-cure temperature), establishedaccording to manufacturer's instructions; (b) T_(i), the initial tooltemperature, usually set at approximately 50% of T_(s) (in ° F. or ° C.)to allow an adequate time span (t₂) between T_(i) and T_(s) and toprovide manufacturing efficiency; (c) P₁, the initial pressure that isgenerally slightly higher than atmospheric pressure and sufficient tohold the component geometry but not sufficient to “squeeze” resin out,in the range of 20-50 psig for example; (d) P₂, the ultimate pressurethat is sufficiently high to ensure dimensional accuracy of components,in the range of 200-300 psig for example; (e) t₁, which is the time atwhich the resin exhibits a minimal viscosity, a function of resinproperties and usually determined by experiment, for most resinsgenerally in the range of 5-10 minutes after first forming the lay-up;(f) t₂, the time of maximum pressure, also a time delay from t₁, whereresin viscosity increases from minimum to approximately 80% of a maximumviscosity (i.e., viscosity of fully cured resin), appears to be relatedto the moment when the tool reaches T_(s); and (g) t₃, the time at theend of the pre-cure cycle, at which the components have reached handlingstrength and resin viscosity is approximately 90% of its maximum.

Many variations of this process also can be designed and may workequally as well. Specifically, all seven parameters mentioned above canbe expressed in terms of ranges instead of specific quantities. In thissense, the processing parameters can be expressed as follows (see FIGS.11A-11C):

T_(s): recommended resin cure temperature±ΔT, where ΔT=20, 50, 75° F.

T_(i): initial tool temperature (or T_(s)/2)±ΔT.

P₁: 0-100 psig±ΔP, where ΔP=5, 10, 15, 25, 35, 50 psi.

P₂: 200-500 psig±ΔP.

t₁: t (minimum ±Δx viscosity)±Δt, where Δx=1, 2, 5, 10, 25% and Δt=1, 2,5, 10 min.

t₂: t (80%±Δx maximum viscosity)±Δt.

t₃: t (90%±Δx maximum viscosity)±Δt.

After reaching full-cure, the components are subjected to manufacturingtechniques (machining, forming, etc.) that achieve the specified finaldimensions, size, contours, etc., of the components for use as faceplates on club-heads. Conventional CNC trimming can be used to removethe sacrificial portion of the fully-cured lay-up (e.g., the portionsurrounding line 64 in FIG. 9). However, because the tool applies alateral cutting force to the part (against the peripheral edge of thepart), it has been found that such trimming can pull fibers or portionsthereof out of their plies and/or induce horizontal cracks on theperipheral edge of the part. These defects can cause prematuredelamination or other failure.

In certain embodiments, the sacrificial portion of the fully-curedlay-up is removed by water-jet cutting. In water-jet cutting, thecutting force is applied in a direction perpendicular to the prepregplies (in a direction normal to the front and rear surfaces of thelay-up), which minimizes the occurrence of cracking and fiber pull out.Consequently, water-jet cutting can be used to increase the overalldurability of the part.

The potential mass “savings” obtained from fabricating at least aportion of the face plate of composite, as described above, is about10-30 g, or more, relative to a 2.7-mm thick face plate formed from atitanium alloy such as Ti-6Al-4V, for example. In a specific example, amass savings of about 15 g relative to a 2.7-mm thick face plate formedfrom a titanium alloy such as Ti-6Al-4V can be realized. As mentionedabove, this mass can be allocated to other areas of the club, asdesired.

FIG. 12 shows a portion of a simplified lay-up 78 that can be used toform the composite part 40 (FIGS. 2-4). The lay-up 78 in this examplecan include multiple prepreg panels (e.g., panels 52 a-52 k) and one ormore clusters 80 of prepreg strips 82. The illustrated cluster 80comprises only four strips 82 of equal width arranged in a criss-crosspattern and which are equally angularly spaced or fanned with respect toeach other about the center of the cluster. Although the figure showsonly one cluster 80, the lay-up desirably includes multiple clusters 80(e.g., 1 to 12 clusters, with 7 clusters in a specific embodiment). Eachcluster is rotated or angularly offset with respect to an adjacentcluster to provide an angular offset between strips of one cluster withthe strips of an adjacent cluster, such as described above, in order toform the reduced-thickness peripheral portion of the lay-up.

The embodiments described thus far provide a face plate having aprojection or cone at the sweet spot. However, various othercross-sectional profiles can be achieved by selective placement ofprepreg strips in the lay-up. FIGS. 13-15, for example, show a compositecomponent 90 for use as a face plate for a club-head (either by itselfor in combination with a polymeric or metal outer layer). The compositecomponent 90 has a front surface 92, a rear surface 94, and an overallslightly convex shape. The reverse surface 94 defines a point 96situated in a central recess 98. The point 96 represents the approximatecenter of the sweet spot of the face plate, not necessarily the centerof the face plate, and is located in the approximate center of therecess 98. The central recess 98 is a “dimple” having a spherical orotherwise radiused sectional profile in this embodiment (see FIGS. 14and 15), and is surrounded by an annular ridge 100. At the point 96 thethickness of the component 90 is less than at the “top” 102 of theannular ridge 100. The top 102 is normally the thickest portion of thecomponent. Outward from the top 102, the thickness of the componentgradually decreases to form a peripheral region 104 of substantiallyuniform thickness surrounding the ridge 100. Hence, the central recess98 and surrounding ridge 100 have a cross-sectional profile that isreminiscent of a “volcano.” Generally speaking, an advantage of thisprofile is that thinner central region is effective to provide a largersweet spot, and therefore a more forgiving club-head.

FIG. 16 is a plan view of a lay-up 110 of multiple prepreg plies thatcan be used to fabricate the composite component 90. FIG. 17 shows anexploded view of a few of the prepreg layers that form the lay-up 110.As shown, the lay-up 110 includes multiple panels 112 a, 112 b, 112 c ofprepreg material and sets, or clusters, 114 a, 114 b, 114 c of prepregstrips interspersed between the panels. The panels 112 a-112 c can beformed from one or more prepreg plies and desirably comprise four plieshaving respective fibers orientations of +45 degrees, 0 degrees, −45degrees, and 90 degrees, in the manner described above. The line 118 inFIGS. 16 and 17 represent the outline of the composite component 90 andthe portion surrounding the line 118 is a sacrificial portion. Once thelay-up 110 is cured, the sacrificial portion surrounding the line 118can be removed to form the component 90.

Each cluster 114 a-114 c in this embodiment comprises four criss-crossstrips 116 arranged in a specific shape. In the illustrated embodiment,the strips of the first cluster 114 a are arranged to form aparallelogram centered on the center of the panel 112 a. The strips ofthe second cluster 114 b also are arranged to form a parallelogramcentered on the center of the panel 112 b and rotated 90 degrees withrespect to the first cluster 114 a. The strips of the third cluster 114c are arranged to form a rectangle centered on the center of panel 112c. When stacked in the lay-up, as best shown in FIG. 16, the strips 116of clusters 114 a-114 c overlay one another so as to collectively forman oblong, annular area of increased thickness corresponding to theannular ridge 100 (FIG. 14). Hence, the fully-formed lay-up has a rearsurface having a central recess and a surrounding annular ridge ofincreased thickness formed collectively by the build up of stripclusters 114 a-114 c. Additional panels 112 a-112 c and strip clusters114 a-114 c may be added to lay-up to achieve a desired thicknessprofile.

It can be appreciated that the number of strips in each cluster can varyand still form the same profile. For example, in the another embodiment,clusters 114 a-114 c can be stacked immediately adjacent each otherbetween adjacent panels 112 (i.e., effectively forming one cluster oftwelve strips 116).

The lay-up 110 may be cured and shaped to remove the sacrificial portionof the lay-up (the portion surrounding the line 118 in FIG. 16representing the finished part), as described above, to form a net shapepart. As in the previous embodiments, each strip 116 is of sufficientlength to extend continuously across the part 90 so that the free endsof the fibers are located on the peripheral edge of the part. In thismanner, the net shape part can be formed free of any voids, or with anextremely low void content (e.g., about 1.7×10⁻⁶ percent or less byvolume) and can have straight fibers in each layer of prepreg material.

As mentioned above, any of various cross-sectional profiles can beachieved by arranging strips of prepreg material in a predeterminedmanner. Examples of other face plate profiles that can be formed by thetechniques described herein are disclosed in U.S. Pat. Nos. 6,800,038,6,824,475, 6,904,663, and 7,066,832, all of which are incorporatedherein by reference.

As mentioned above, the face plate 12 (FIG. 1) can include a compositeplate and a metal cap covering the front surface of the composite plate.One such embodiment is shown, for example, in the partial sectiondepicted in FIG. 18, in which the face plate 12 comprises a metal “cap”130 formed or placed over a composite plate 40 to form the strikesurface 13. The cap 130 includes a peripheral rim 132 that covers theperipheral edge 134 of the composite plate 40. The rim 132 can becontinuous or discontinuous, the latter comprising multiple segments(not shown).

The metal cap 130 desirably is bonded to the composite plate 40 using asuitable adhesive 136, such as an epoxy, polyurethane, or film adhesive.The adhesive 136 is applied so as to fill the gap completely between thecap 130 and the composite plate 40 (this gap usually in the range ofabout 0.05-0.2 mm, and desirably is approximately 0.1 mm). The faceplate 12 desirably is bonded to the body 14 using a suitable adhesive138, such as an epoxy adhesive, which completely fills the gap betweenthe rim 132 and the adjacent peripheral surface 140 of the face support18 and the gap between the rear surface of the composite plate 40 andthe adjacent peripheral surface 142 of the face support 18.

A particularly desirable metal for the cap 130 is titanium alloy, suchas the particular alloy used for fabricating the body (e.g., Ti-6Al-4V).For a cap 130 made of titanium alloy, the thickness of the titaniumdesirably is less than about 1 mm, and more desirably less than about0.3 mm. The candidate titanium alloys are not limited to Ti-6Al-4V, andthe base metal of the alloy is not limited to Ti. Other materials or Tialloys can be employed as desired. Examples include commercially pure(CP) grade Ti, aluminum and aluminum alloys, magnesium and magnesiumalloys, and steel alloys.

Surface roughness can be imparted to the composite plate 40 (notably toany surface thereof that will be adhesively bonded to the body of theclub-head and/or to the metal cap 130). In a first approach, a layer oftextured film is placed on the composite plate 40 before curing the film(e.g., “top” and/or “bottom” layers discussed above). An example of sucha textured film is ordinary nylon fabric. Conditions under which theadhesives 136, 138 are cured normally do not degrade nylon fabric, sothe nylon fabric is easily used for imprinting the surface topography ofthe nylon fabric to the surface of the composite plate. By impartingsuch surface roughness, adhesion of urethane or epoxy adhesive, such as3M® DP 460, to the surface of the composite plate so treated is improvedcompared to adhesion to a metallic surface, such as cast titanium alloy.

In a second approach, texture can be incorporated into the surface ofthe tool used for forming the composite plate 40, thereby allowing thetextured area to be controlled precisely and automatically. For example,in an embodiment having a composite plate joined to a cast body, texturecan be located on surfaces where shear and peel are dominant modes offailure.

FIG. 19 shows an embodiment similar to that shown in FIG. 18, with onedifference being that in the embodiment of FIG. 19, the face plate 12includes a polymeric outer layer, or cap, 150 on the front surface ofthe composite plate 40 forming the striking surface 13. The outer layer150 desirably completely covers at least the entire front surface of thecomposite plate 40. A list of suitable polymers that can be used as anouter layer on a face plate is provide below. A particularly desirablepolymer is urethane. For an outer layer 150 made of urethane, thethickness of the layer desirably is in the range of about 0.2 mm toabout 1.2 mm, with about 0.4 mm being a specific example. As shown, theface plate 12 can be adhesively secured to the face support 18 by anadhesive 138 that completely fills the gap between the peripheral edge134 and the adjacent peripheral surface 140 of the face support 18 andthe gap between the rear surface of the composite plate 40 and theadjacent peripheral surface 142 of the face support 18.

The composite face plate as described above need not be coextensive(dimensions, area, and shape) with a typical face plate on aconventional club-head. Alternatively, a subject composite face platecan be a portion of a full-sized face plate, such as the area of the“sweet spot.” Both such composite face plates are generally termed “faceplates” herein. Further, the composite plate 40 itself (withoutadditional layers of material bonded or formed on the composite plate)can be used as the face plate 12.

EXAMPLE 1

In this example, a number of composite strike plates were formed usingthe strip approach described above in connection with FIGS. 2-9. Anumber of strike plates having a similar profile were formed using thepartial ply approach described above. Five plates of each batch weresectioned and optically examined for voids. Table 1 below reports theyield of the examined parts. The yield is the percentage of parts madethat did not contain any voids. As can be seen, the strip approachprovided a much greater yield of parts without voids than the partialply approach. The remaining parts of each batch were then subjected toendurance testing during which the parts were subjected to 3600 impactsat a ball speed of 50 m/s. As shown in Table 1, the parts made by thestrip approach yielded a much higher percentage of parts that survived3600 impacts than the parts made by the partial ply approach (72.73% vs.52%). Table 1 also shows the average characteristic time (CT) (ballcontact time with the strike plate) measured during the endurance test.

TABLE 1 Number Average of % of weight Yield CT Pieces passing passingMaximum (g) (%) (μs) tested parts parts shots Strip 21.9 81 255 11 872.73 3600 Partial 21.6 57.5 259 25 13 52 3600 ply

EXAMPLE 2

In this example, a number of composite strike plates were formed usingthe strip approach described above in connection with FIGS. 2-9. Anumber of strike plates having a similar profile were formed using thepartial ply approach above. Five plates of each batch were sectioned andoptically examined for voids. Table 2 below reports the yield of theparts formed by both methods. As in Example 1, the strip approachprovided a much greater yield of parts without voids than the partialply approach (90% vs. 70%). The remaining parts of each batch were thensubjected to endurance testing during which the parts were subjected to3600 impacts at a ball speed of 42 m/s. At this lower speed, all of thetested parts survived 3600 impacts.

TABLE 2 Number Average of % of weight Yield CT Pieces passing passingMaximum (g) (%) (μs) tested parts parts shots Strip 22 90 255 11 11 1003600 Partial 21.5 70 258 16 16 100 3600 ply

The methods described above provide improved structural integrity of theface plates and other club-head components manufactured according to themethods, compared to composite component manufactured by prior-artmethods. These methods can be used to fabricate face plates for any ofvarious types of clubs, such as (but not limited to) irons, wedges,putter, fairway woods, etc., with little to no process-parameterchanges.

The subject methods are especially advantageous for manufacturing faceplates because face plates are the most severely loaded components ingolf club-heads. If desired, conventional (and generally less expensive)composite-processing techniques (e.g., bladder-molding, etc.) can beused to make other parts of a club-head not subject to such severeloads.

Moreover, the methods for fabricating composite parts described hereincan be used to make various other types of composite parts, and inparticular, parts that are subject to high impact loads and/orrepetitive loads. Some examples of such parts include, withoutlimitation, a hockey stick (e.g., the blade of a stick), a bicycleframe, a baseball bat, and a tennis racket, to name a few.

EXAMPLE 3

As shown in FIGS. 18-19, a metallic cover can be provided so that a golfclub striking plate includes a composite face plate and a metallicstriking surface that tends to be wear resistant. A representativemetallic cover 160 is illustrated in detail in FIGS. 20-23. Referring toFIG. 20, the metallic cover 160 provides a striking surface 161 thatincludes a central striking region 162 and a plurality of contrastingscorelines 164 a-164 j that are associated with respective dents,depressions, or indentations in the metallic cover that are generallyfilled with a contrasting pigment or paint such as white paint.Scorelines generally extend along an axis parallel to a toe-to-heeldirection. In a representative example, scorelines have lengths ofbetween about 6 mm and 14 mm, with scoreline lengths larger toward agolf club crown. The scorelines are spaced about 6-7 mm apart in atop-to-bottom direction. The arrangement of FIG. 20 is one example, andother arrangements can be used.

The metallic cover 160 is generally made of a titanium alloy or othermetal such as those mentioned above, and has a bulge/roll center 166 forbulge and roll curvatures that are provided to control club performance.Centers of curvature for bulge/roll curvatures are typically situated onan axis that is perpendicular to the striking surface 161 at thebulge/roll center 166. In this example, innermost edges of thescorelines 164 a-164 j are situated along a circumference of a circlehaving a diameter of about 40-50 mm that is centered at the bulge/rollcenter 166. As shown in the sectional view of FIG. 21, a “roll” radiusof curvature (a top-to-bottom radius of curvature) is about 300 mm andis symmetric about the bulge/roll center. As shown in the sectional viewof FIG. 22, a “bulge” radius of curvature (a toe-to-heel radius ofcurvature) is about 410 mm and is symmetric about the bulge/roll center166. Bulge and roll curvatures can be spherical or circular curvatures,but other curvatures such as elliptical, oval, or other curvatures canbe provided. In this example, a rim 168 is provided and is intended toat least partially cover an edge of a composite faceplate to which themetallic cover 160 is attached.

The striking region 162 can be roughened by sandblasting, bead blasting,sanding, or other abrasive process or by a machining or other process.The scorelines 164 a-164 j are situated outside of the intended strikingregion 162 and are generally provided for visual alignment and do nottypically contribute to ball trajectory. A cross-section of arepresentative scoreline 164 a is shown in FIG. 23 (paint or otherpigment is not shown). The scoreline 164 a is provided as an indentationin the cover 160 and includes transition portions 170, 174 and a bottomportion 172. For a thin cover plate (thickness less than about 1.0 mm,0.5 mm, 0.3 mm, or 0.2 mm), the scoreline 164 a can be formed bypressing a correspondingly shaped tool against a sheet of a selectedcover plate material. An overall curvature for the cover 160 can also beprovided in the same manner based on a bulge and roll of a face platesuch as a composite face plate to which the cover 160 is to be applied.For a typical cover thickness, indented scorelines are associated withcorresponding protruding features on a rear surface 176 of the cover160. In this example, the scoreline 164 a has a depth D of about 0.07 mmin a cover having a thickness T of about 0.30 mm. A width W_(B) of thebottom portion 172 is about 0.29 mm, and a width W_(G) of the entireindent is about 0.90 mm. The transition portions 170, 174 have inner andouter radiused regions 181, 185 and 180, 184, respectively, havingrespective radii of curvature of about 0.40 mm and 0.30 mm.

In other examples, a cover can be between about 0.10 mm and 1.0 mmthick, between about 0.2 mm and 0.8 mm thick, or between about 0.3 mmand 0.5 mm thick. Indentation depths between about 0.02 mm and 0.12 mmor about 0.06 mm and 0.10 mm are generally preferred for scorelinedefinition. Impact resistant cover plates with scorelines generally havescoreline depths D and cover plate thicknesses T such that a ratio D/Tis less than about 0.4, 0.3, 0.25, or 0.20. A ratio W_(B)/T is typicallybetween about 0.5 and 1.5, 0.75 and 1.25, or 0.9 and 1.1. A ratioW_(G)/T is typically between about 1 and 5, 2 and 4, or 2.5 and 3.5. Aratio of transition region radii of curvature R to cover thickness T istypically between about 0.5 and 1.5, 0.67 and 1.33, or 0.75 and 1.33.While it is convenient to provide scorelines based on common indentationdepths, scorelines on a single cover can be based on indentations of oneor more depths.

For wood-type golf clubs, an impact area is based on areas associatedwith inserts used in traditional wood golf clubs. For irons, an impactarea is a portion of the striking surface within 20 mm on either side ofa vertical centerline, but does not include 6.35 mm wide strips at thetop and bottom of the striking surface. For wood-type golf clubs,scorelines are generally provided in a cover so as to be situatedexterior to an impact region. The disclosed covers with scorelines aresufficiently robust for placement within or without an impact region foreither wood or iron type golf clubs.

A cover is generally formed from a sheet of cover stock that isprocessed so as to have a bulge/roll region that includes the necessaryarrangement of scoreline dents. The formed cover stock is then trimmedto fit an intended face plate, and attached to the face plate with anadhesive. Typically a glue layer is situated between the cover and theface plate, and the cover and face plate are urged together so as toform an adhesive layer of a suitable thickness. For typical adhesives,layer thicknesses between about 0.05 mm and 0.10 mm are preferred. Oncea suitable layer thickness is achieved, the adhesive can be cured orallowed to set. In some cases, the cover includes a cover lip or rim aswell so as to cover a face plate perimeter. The scoreline indentationsare generally filled with paint of a color that contrasts with theremainder of the striking surface.

Although the scorelines are provided to realize a particular appearancein a finished product, the indentations used to define the scorelinesalso serve to control adhesive thickness. As a cover plate and a faceplate are urged together in a gluing operation, the rear surfaceprotrusions associated with the indentations tend to approach the faceplate and thus regulate an adhesive layer thickness. Accordingly,indentation depth can be selected not only to retain paint or otherpigment on a striking face, but can also based on a preferred adhesivelayer thickness. In some examples, protruding features of indentationsin a cover plate are situated at distances of less than about 0.10 mm,0.05 mm, 0.03 mm, and 0.01 mm from a face plate surface as an adhesivelayer thickness is established.

In other examples, the indent-based scorelines shown in FIGS. 20-23 canbe replaced with grooves that are punched, machined, etched or otherwiseformed in a cover plate sheet. Indentations are generally preferable asgluing operations based on indented plates are not generally associatedwith adhesive transfer to the striking surface. In addition, strikingplates made with dented metallic covers tend to be more stable in longterm use than cover plates that have been machined or punched. Scorelineor indent dimensions (length, depth, and transition region dimensionsand curvatures) as well as scoreline or indentation location on astriking surface are preferably selected based on a selected covermaterial or cover material thickness. Fabrication methods (such aspunching, machining) tend to produce cover plates that are more likelyto show wear under impact endurance testing in which a finished strikingplate is subject to the forces associated with 3000 shots by, forexample, forming a club head with a striking plate under test, andmaking 3000 shots with the club head. A cover that performs successfullyunder such testing without degradation is referred as animpact-resistant cover plate.

In alternative embodiments, a cover includes a plurality of slotssituated around a striking region. A suitably colored adhesive can beused to secure the cover layer to a face plate so that the adhesivefills the slots or is visible through the slots so to provide visibleorientation guides on the striking plate surface.

EXAMPLE 4

Polymer or other surface coatings or surface layers can be provided tocomposite or other face plates to provide performance similar to that ofconventional irons and metal type woods. Such surface layers, methods offorming such layers, and characterization parameters for such layers aredescribed below.

Surface Texture and Roughness

Surface textures or roughness can be conveniently characterized based asurface profile, i.e., a surface height as a function of position on thesurface. A surface profile is typically obtained by interrogating asample surface with a stylus that is translated across the surface.Deviations of the stylus as a function of position are recorded toproduce the surface profile. In other examples, a surface profile can beobtained based on other contact or non-contact measurements such as withoptical measurements. Surface profiles obtained in this way are oftenreferred to as “raw” profiles. Alternatively, surface profiles for agolf club striking surface can be functionally assessed based on shotcharacteristics produced when struck with surfaces under wet conditions.

For convenience, a control layer is defined as a striking face coverlayer configured so that shots are consistent under wet and dry playingconditions. Generally, satisfactory roughened or textured strikingsurfaces (or other control surfaces) provide ball spins of at leastabout 2000 rpm, 2500 rpm, 3000 rpm, or 3500 rpm under wet conditionswhen struck with club head speeds of between about 75 mph and 120 mph.Such control surfaces thus provide shot characteristics that aresubstantially the same as those obtained with conventional metal woods.Stylus or other measurement based surface roughness characterizationsfor such control surfaces are described in detail below.

A surface profile is generally processed to remove gradual deviations ofthe surface from flatness. For example, a wood-type golf club strikingface generally has slight curvatures from toe-to-heel and crown-to-soleto improve ball trajectory, and a “raw” surface profile of a strikingsurface or a cover layer on the striking surface can be processed toremove contributions associated with these curvatures. Other slow (i.e.,low spatial frequency) contributions can also be removed by suchprocessing. Typically features of size of about 1 mm or greater (orspatial frequencies less than about 1/mm) can be removed by processingas the contributions of these features to ball spin about a horizontalor other axis tend to be relatively small. A raw (unprocessed) profilecan be spatially filtered to enhance or suppress high or low spatialfrequencies. Such filtering can be required in some measurements toconform to various standards such as DIN or other standards. Thisfiltering can be performed using processors configured to execute a FastFourier Transform (FFT).

Generally, a patterned roughness or texture is applied to a substantialportion of a striking surface or at least to an impact area. Forwood-type golf clubs, an impact area is based on areas associated withinserts used in traditional wood golf clubs. For irons, an impact areais a portion of the striking surface within 20 mm on either side of avertical centerline, but does not include 6.35 mm wide strips at the topand bottom of the striking surface. Generally, such patterned roughnessneed not extend across the entire striking surface and can be providedonly in a central region that does not extend to a striking surfaceperimeter. Typically for hollow metal woods, at least some portions ofthe striking surface at the striking surface perimeter lack patternroughness in order to provide an area suitable for attachment of thestriking plate to the head body.

Striking surface roughness can be characterized based on a variety ofparameters. A surface profile is obtained over a sampling length of thestriking surface and surface curvatures removed as noted above. Anarithmetic mean R_(a) is defined a mean value of absolute values ofprofile deviations from a mean line over a sampling length of thesurface. For a surface profile over the sampling length that includes Nsurface samples each of which is associated with a mean value ofdeviations Y_(i), from the mean line, the arithmetic mean R_(a) is:

${R_{a} = {\frac{1}{N}{\sum\limits_{i = 1}^{N}{Y_{i}}}}},$wherein i is an integer i=1, . . . , N. The sampling length generallyextends along a line on the striking surface over a substantial portionor all of the striking area, but smaller samples can be used, especiallyfor a patterned roughness that has substantially constant propertiesover various sample lengths. Two-dimensional surface profiles can besimilarly used, but one dimensional profiles are generally satisfactoryand convenient. For convenience, this arithmetic mean is referred toherein as a mean surface roughness.

A surface profile can also be further characterized based on areciprocal of a mean width S_(m) of the profile elements. This parameteris used and described in one or more standards set forth by, forexample, the German Institute for Standardization (DIN) or theInternational Standards Organization (ISO). In order to establish avalue for S_(m), an upper count level (an upward surface deviationassociated with a peak) and a lower count level (a downward surfacedeviation associated with a valley) are defined. Typically, the uppercount level and the lower count level are defined as values that are 5%greater than the mean line and 5% less than the mean line, but othercount levels can be used. A portion of a surface profile projectingupward over the upper count level is called a profile peak, and aportion projecting downward below the given lower count level is calleda profile valley. A width of a profile element is a length of thesegment intersecting with a profile peak and the adjacent profilevalley. S_(m) is a mean of profile element widths S_(mi) within asampling length:

$S_{m} = {\frac{1}{K}{\sum\limits_{i = 1}^{K}S_{m\; i}}}$For convenience, this mean is referred to herein as a mean surfacefeature width.

In determining S_(m), the following conditions are generallysatisfied: 1) Peaks and valleys appear alternately; 2) An intersectionof the profile with the mean line immediately before a profile elementis the start point of a current profile element and is the end point ofa previous profile element; and 3) At the start point of the samplinglength, if either of the profile peak or profile valley is missing, theprofile element width is not taken into account. Rpc is defined as areciprocal of the mean width S_(m) and is referred to herein as meansurface feature frequency.

Another surface profile characteristic is a surface profile kurtosis Kuthat is associated with an extent to which profile samples areconcentrated near the mean line. As used herein, a the profile kurtosisKu is defined as:

${{Ku} = {\frac{1}{R_{q}^{4}}\bullet\frac{1}{N}{\sum\limits_{i = 1}^{N}\left( Y_{i} \right)^{4}}}},$wherein R_(q) a square root of the arithmetic mean of the squares of theprofile deviations from the mean line, i.e.,

$R_{q} = {\left( {\frac{1}{N}{\sum\limits_{i = 1}^{N}Y_{i}^{2}}} \right)^{1/2}.}$

Profile kurtosis is associated with an extent to which surface featuresare pointed or sharp. For example, a triangular wave shaped surfaceprofile has a kurtosis of about 0.79, a sinusoidal surface profile has akurtosis of about 1.5, and a square wave surface profile has a kurtosisof about 1.

Other parameters that can be used to characterize surface roughnessinclude R_(z) which is based on a sum of a mean of a selected number ofheights of the highest peaks and a mean of a corresponding number ofdepths of the lowest valleys.

One or more values or ranges of values can be specified for surfacekurtosis Ku, mean surface feature width S_(m), and arithmetic meandeviation R_(a) (mean surface roughness) for a particular golf clubstriking surface. Superior results are generally obtained with R_(a)≦5μm, R_(pc)≧30/cm, and K_(u)≧2.0.

Wood-Type Club Heads

For convenient illustration, representative examples of striking platesand cover layers for such striking plates are set forth below withreference to wood-type golf clubs. In other examples, such strikingplates can be used in iron-type golf clubs. In some examples, face platecover layers are formed on a surface of a face plate in a moldingprocess, but in other examples surface layers are provided as caps thatare formed and then secured to a face plate.

As illustrated in FIGS. 24-27, a typical wood type (i.e., driver orfairway wood) golf club head 205 includes a hollow body 210 delineatedby a crown 215, a sole 220, a skirt 225, a striking plate 230, and ahosel 235. The striking plate 230 defines a front surface, or strikingface 240 adapted for impacting a golf ball (not shown). The hosel 235defines a hosel bore 237 adapted to receive a golf club shaft (notshown). The body 210 further includes a heel portion 245, a toe portion250 and a rear portion 255. The crown 215 is defined as an upper portionof the club head 5 extending above a peripheral outline 257 of the clubhead as viewed from a top-down direction and rearwards of the topmostportion of the striking face 240. The sole 220 is defined as a lowerportion of the club head 205 extending in an upwardly direction from alowest point of the club head approximately 50% to 60% of the distancefrom the lowest point of the club head to the crown 215. The skirt 225is defined as a side portion of the club head 205 between the crown 215and the sole 220 extending immediately below the peripheral outline 257of the club head, excluding the striking face 240, from the toe portion250, around the rear portion 255, to the heel portion 245. The club head205 has a volume, typically measured in cubic-centimeters (cm³), equalto the volumetric displacement of the club head 205.

Referencing FIGS. 28-29, club head coordinate axes can be defined withrespect to a club head center-of-gravity (CG) 280. A CG_(z)-axis 285extends through the CG 280 in a generally vertical direction relative tothe ground 299 when the club head 205 is at address position. ACG_(x)-axis 290 extends through the CG 280 in a heel-to-toe directiongenerally parallel to the striking face 240 and generally perpendicularto the CG_(z)-axis 285. A CG_(y)-axis 95 extends through the CG 280 in afront-to-back direction and generally perpendicular to the CG_(x)-axis290 and the CG_(z)-axis 285. The CG_(x)-axis 290 and the CG_(y)-axis 295both extend in a generally horizontal direction relative to the groundwhen the club head 5 is at address position. The polymer coated orcapped striking plates described herein generally provide 2-15 g ofadditional distributable mass so that placement of the CG 280 can beselected using this mass.

A club head origin coordinate system can also be used. Referencing FIGS.30-31, a club head origin 260 is represented on club head 205. The clubhead origin 260 is positioned at an approximate geometric center of thestriking face 240 (i.e., the intersection of the midpoints of thestriking face's height and width, as defined by the USGA “Procedure forMeasuring the Flexibility of a Golf Clubhead,” Revision 2.0).

The head origin coordinate system, with head origin 260, includes threeaxes: a z-axis 265 extending through the head origin 260 in a generallyvertical direction relative to the ground 100 when the club head 205 isat address position; an x-axis 270 extending through the head origin 60in a heel-to-toe direction generally parallel to the striking face 240and generally perpendicular to the z-axis 265; and a y-axis 275extending through the head origin 260 in a front-to-back direction andgenerally perpendicular to the x-axis 270 and the z-axis 265. The x-axis270 and the y-axis 275 both extend in a generally horizontal directionrelative to the ground 299 when the club head 205 is at addressposition. The x-axis 270 extends in a positive direction from the origin260 to the toe 250 of the club head 205; the y-axis 275 extends in apositive direction from the origin 260 towards the rear portion 255 ofthe club head 205; and the z-axis 265 extends in a positive directionfrom the origin 260 towards the crown 215.

In a club-head according to one embodiment, a striking plate includes aface plate and a cover layer. In addition, in some examples, at least aportion of the face plate is made of a composite including multipleplies or layers of a fibrous material (e.g., graphite, or carbon, fiber)embedded in a cured resin (e.g., epoxy). Examples of suitable polymersthat can be used to form the cover layer include, without limitation,urethane, nylon, SURLYN ionomers, or other thermoset, thermoplastic, orother materials. The cover layer defines a striking surface that isgenerally a patterned, roughened, and/or textured surface as describedin detail below. Striking plates based on composites typically permit amass reduction of between about 5 g and 20 g in comparison with metalstriking plates so that this mass can be redistributed.

In the example shown in FIGS. 32-34, a striking plate 380 includes aface plate 381 fabricated from a plurality of prepreg plies or layersand has a desired shape and size for use in a club-head. The face plate381 has a front surface 382 and a rear surface 344. In this example, theface plate 381 has a slightly convex shape, a central region 346 ofincreased thickness, and a peripheral region 348 having a relativelyreduced thickness extending around the central region 346. The centralregion 346 in the illustrated example is in the form of a projection orcone on the rear surface having its thickest portion at a central point350 and gradually tapering away from the point in all directions towardthe peripheral region 348. The central point 350 represents theapproximate center of the “sweet spot” (optimal strike zone) of thestriking plate 380, but not necessarily the geometric center of the faceplate 381. The thicker central region 348 adds rigidity to the centralarea of the face plate 381, which effectively provides a more consistentdeflection across the face plate. In certain embodiments, the face plate381 is fabricated by first forming an oversized a lay-up of multipleprepreg plies that are subsequently trimmed or otherwise machined.

As shown in FIGS. 33-34, a cover layer 360 is situated on the frontsurface 382 of the face plate 381. The cover layer 360 includes a rearsurface 362 that is typically conformal with and bonded to the frontsurface 382 of the face plate 381, and a striking surface 364 that istypically provided with patterned roughness so as to control or select ashot characteristic so as to provide performance similar to thatobtained with conventional club construction. The cover layer 360 can beformed of a variety of polymers such as, for example, SURLYN ionomers,urethanes, or others. Representative polymers are disclosed in U.S.patent application Ser. Nos. 11/685,335, filed Mar. 13, 2007 and11/809,432, filed May 31, 2007 that are incorporated herein byreference. These polymers are discussed with reference to golf balls,but are also suitable for use in striking plates as described herein. Insome examples, the cover layer 360 can be co-cured with the prepreglayers that form the face plate 381. In other examples, the cover layer360 is formed separately and then bonded or glued to the face plate 381.The cover layer 362 can be selected to provide wear resistance orultraviolet protection for the face plate 381, or to include a patternedstriking surface that provides consistent shot characteristics duringplay in both wet and dry conditions. Typically, surface textures and/orpatterning are configured so as to substantially duplicate the shotcharacteristics achieved with conventional wood clubs or metal wood typeclubs with metallic striking plates. To enhance wear resistance, a ShoreD hardness of the cover layer 360 is preferably sufficient to provide astriking face effective hardness with the polymer layer applied of atleast about 75, 80, or 85. In typical examples, a thickness of the coverlayer 360 is between about 0.1 mm and 3.0 mm, 0.15 mm and 2.0 mm, or 0.2mm and 1.2 mm. In some examples, the cover layer 360 is about 0.4 mmthick.

Club face hardness or striking face hardness is generally measured basedon a force required to produce a predetermined penetration of a probe ofa standard size and/or shape in a selected time into a striking face ofthe club, or a penetration depth associated with a predetermined forceapplied to the probe. Based on such measurements, an effective Shore Dhardness can be estimated. For the club faces described herein, theShore D hardness scale is convenient, and effective Shore D hardnessesof between about 75 and 90 are generally obtained. In general, measuredShore D values decrease for longer probe exposures. Club face hardnessesas described herein are generally based on probe penetrations sufficientto produce an effective hardness estimate (an effective Shore D value)that can be associated with shot characteristics substantially similarto conventional wood or metal wood type golf clubs. The effectivehardness generally depends on faceplate and polymer layer thicknessesand hardnesses.

As shown in FIG. 35, a striking plate 312 comprises a cover layer 330formed or placed over a composite face plate 340 to form a strikingsurface 313. In other examples, the cover layer 330 can include aperipheral rim that covers a peripheral edge 334 of the composite faceplate 340. The rim 332 can be continuous or discontinuous, the lattercomprising multiple segments (not shown). The cover layer 330 can bebonded to the composite plate 340 using a suitable adhesive 336, such asan epoxy, polyurethane, or film adhesive, or otherwise secured. Theadhesive 336 is applied so as to fill the gap completely between thecover layer 330 and the composite plate 340 (this gap is usually in therange of about 0.05-0.2 mm, and desirably is less than approximately0.05 mm). Typically the cover layer 330 is formed directly on the faceplate, and the adhesive 336 is omitted. The striking plate 312 desirablyis bonded to a club body 314 using a suitable adhesive 338, such as anepoxy adhesive, which completely fills the gap between the rim 332 andthe adjacent peripheral surface 338 of the face support 318 and the gapbetween the rear surface of the composite plate 340 and the adjacentperipheral surface 342 of the face support 318. In the example of FIG.35, the cover layer 330 extends at least partially around a faceplateedge, but in other examples, a cover layer is situated only on anexternal surface of the face plate. As used herein, an external surfaceof a face plate is a face plate surface directed towards a ball innormal address position. In conventional metallic striking plates thatconsist only of a metallic face plate, the external surface is thestriking surface.

Cover layers such as the cover layer 330 can be formed and secured to aface plate using various methods. In one example, a striking surface ofa cover layer is patterned with a mold. A selected roughness pattern isetched, machined, or otherwise transferred to a mold surface. The moldsurface is then used to shape the striking surface of the cover layerfor subsequent attachment to a composite face plate or other face plate.Such cover layers can be bonded with an adhesive to the face plate.Alternatively, the mold can be used to form the cover layer directly onthe composite part. For example, a layer of a thermoplastic material (orpellets or other portions of such a material) can be situated on anexternal surface of a face plate, and the mold pressed against thethermoplastic material and the face plate at suitable temperatures andpressures so as to impress the roughness pattern on a thermoplasticlayer, thereby forming a cover layer with a patterned surface. Inanother example, a thermoset material can be deposited on the externalsurface of the cover plate, and the mold pressed against the thermosetmaterial and the face plate to provide a suitable cover layer thickness.The face plate, the thermoset material, and the mold are then raised toa suitable temperature so as to cure or otherwise fix the shape andthickness of the cover layer. These methods are examples only, and othermethods can be used as may be convenient for various cover materials.

In another method, a layer of a so-called “peel ply” fabric is bonded toan exterior surface of a composite face plate (preferably as the faceplate is fabricated) or to a striking surface on a polymer cover layer.In some examples, a thermoset material is used for the cover layer,while in other examples thermoplastic materials are used. With eithertype of material, the peel ply fabric is removably bonded to the coverlayer (or to the face plate). The peel ply fabric is removed from thecover layer, leaving a textured or roughened striking surface. Astriking surface texture can be selected based upon peel ply fabrictexture, fabric orientation, and fiber size so as to achieve surfacecharacteristics comparable to conventional metal woods and irons.

A representative peel ply based process is illustrated in FIGS. 40-42. Aportion of a peel ply fabric 602 is oriented so the woven fibers in thefabric are along an x-axis 604 and a z-axis 606 based on an eventualstriking plate orientation in a finished club. In other examples,different orientations can be used. Peel ply fabric weave is notgenerally or necessarily the same along the warp and the weftdirections, and in some examples, the warp and weft are alignedpreferentially along selected directions. As shown in FIG. 41, aresulting striking plate 610 includes a face plate 612 and a cover layer614 that has a textured striking surface 616. A portion of the texturedstriking surface 616 is shown in FIG. 42 to illustrate the surfacetexture based on surface peaks 618 that are separated by about 0.27 mmand having a height H of about 0.03 mm. In the example of FIGS. 40-42,the cover layer 610 is about 0.5 mm thick.

Representative surface profiles of peel ply based striking surfaces areshown in FIGS. 43-44. FIG. 43 is portion of a toe-to-heel surfaceprofile scan performed with a stylus-based surface profilometer asdescribed further detail above. Relatively rough profile portions 702are separated by profile portions 704 that correspond to more gradualsurface curvatures. A plurality of peaks 706 in the rough profileportions 702 appear to correspond to a stylus crossing over featuresdefined by individual peel ply fabric fibers. The smoother portions 704appear to correspond to stylus scanning along a feature that is definedalong a fiber direction. Surface peaks have a periodic separation ofabout 0.5 mm and a height of about 20-30 μm. FIG. 44 is a portion of asimilar scan to that of FIG. 43 but along a top-to-bottom direction.Relatively smooth and rough areas alternate, and peak spacing is about0.6 mm, slightly larger than that in the toe-to-heel direction, likelydue to differing fiber spacings in peel ply fabric warp and weft. FIG.45 is a photograph of a portion of a striking surface formed with a peelply fabric.

An example striking plate 810 based on a machined or other mold is shownin FIGS. 46-48. In this example, a surface texture 811 provided to astriking surface 816 is aligned with respect to a club and a club headsubstantially along an x-axis as shown in FIG. 46. FIGS. 47-48illustrate the texture 811 of the striking surface 816 that is formed asa surface of a cover layer 814 that is situated on a face plate 812. Asshown in FIG. 48, the cover layer 814 is about 0.5 mm thick, and thetexture includes a plurality of valleys 818 separated by about 0.34 mmand about 40 μm deep. FIG. 49 includes a portion of a stylus-basedtop-to-bottom surface scan of a representative polymer surface showingbumps having a center to center spacing of about 0.34 mm.

The following table summarize surface roughness parameters associatedwith the scans of FIGS. 43-44 and 49. In typical examples, measuredsurface roughness is greater than about 0.1 μm, 1 μm, 2 μm, or 2.5 μmand less than about 20 μm, 10 μm, 5 μm, 4.5 μm, or 4 μm.

Toe-to-Heel Scan Toe-to-Heel Scan Top-to-Bottom Scan Parameter (TooledMold) (Peel Ply Shaped) (Peel Ply Shaped) R_(a) 6.90 μm 8.31 μm 7.07 μmR_(z) 29.4 μm 49.0 μm 48.7 μm R_(p)  9.9 μm 26.9 μm 27.4 μm RPc 29.7/cm44.4/cm 37.6/cm K_(u) 2.41

A striking surface of a cover layer can be provided with a variety ofother roughness patterns some examples of which are illustrated in FIGS.36-39. Typically these patterns extend over substantially the entirestriking surface, but in some illustrated examples only a portion of thestriking surface is shown for convenient illustration. Referring toFIGS. 36-37, a striking plate 402 includes a composite face plate 403and a cover layer 404. A striking surface 409 of the cover layerincludes a patterned area 410 that includes a plurality of patternfeatures 412 that are arranged in a two dimensional array. As shown inFIGS. 36-37, the pattern features 412 are rectangular or squaredepressions formed in the cover layer 404 and that extend along a+y-direction (i.e., inwardly towards an external surface 414 of the faceplate 403). A horizontal spacing (along an x-axis 420) of the patternfeatures is dx and a vertical spacing (along a z-axis 422) is dz. Thesespacings can be the same or different, and the features 412 can beinwardly or outwardly directed and can be columns or depressions havingsquare, circular, elliptical, polygonal, oval, or other cross-sectionsin an xz-plane. In addition, for cross-sectional shapes that areasymmetric, the pattern features can be arbitrarily aligned with respectto the x-axis 420 and the z-axis 422. The pattern features 412 can belocated in a regular array, but the orientation of each of the patternfeatures can be arbitrary, or the pattern features can be periodicallyarranged along the x-axis 420, the z-axis 422, or another axis in thexz-plane. As shown in FIG. 36, a plurality of scorelines 430 areprovided and are typically colored so as to provide a high contrast. Amaximum depth dy of the pattern features 512 along the y-axis is betweenabout 10 μm and 100 μm, between about 5 μm and 50 μm, or about 2 μm and25 μm. The horizontal and vertical spacings are typically between about0.025 mm and 0.500 mm

While the pattern features 412 may have substantially constantcross-sectional dimensions in one or more planes perpendicular thexz-plane (i.e. vertical cross-sections), these vertical cross-sectionscan vary along a y-axis 424 or as a function of an angle of across-sectional plane with respect to the x-axis, the y-axis, or thez-axis. For example, columnar protrusions can have bases that taperoutwardly, inwardly, or a combination thereof along the y-axis 424, andcan be tilted with respect to the y-axis 424.

In an example shown in FIGS. 38-39, a cover layer 504 includes aplurality of pattern features 512 that are periodically situated alongan axis 514 that is tilted with respect to an x-axis 520 and a z-axis522. The pattern features 512 are periodic in one dimension, but inother examples, pattern features periodic along one more axes that aretilted (or aligned with) x- and z-axes can be provided. A plurality ofscorelines 530 are provided (generally in a face plate) and are coloredso as to provide a high contrast. As shown in FIG. 39, the cover layer504 is secured to a face plate 503 and the pattern features 512 have adepth dy.

In other examples, pattern features can be periodic, aperiodic, orpartially periodic, or randomly situated. Spatial frequencies associatedwith pattern features can vary, and pattern feature size and orientationcan vary as well. In some examples, a roughened surface is defined asseries of features that are randomly situated and sized.

Similar striking plates can be provided for iron-type golf clubs. Whilestriking plates for wood-type golf clubs generally have top-to-bottomand toe-to-heel curvatures (commonly referred to as bulge and roll),striking plates for irons are typically flat. Composite-based strikingplates for iron-type clubs typically include a polymer cover layerselected to protect the underlying composite face plate. In someexamples, similar striking surface textures to those described above canbe provided. In addition, one or more conventional grooves are generallyprovided on the striking surface. Such striking plates can be secured toiron-type golf club bodies with various adhesives or otherwise secured.

Representative Polymer Materials

Representative polymer materials suitable for face plate covers or capsare described herein.

DEFINITIONS

The term “bimodal polymer” as used herein refers to a polymer comprisingtwo main fractions and more specifically to the form of the polymer'smolecular weight distribution curve, i.e., the appearance of the graphof the polymer weight fraction as a function of its molecular weight.When the molecular weight distribution curves from these fractions aresuperimposed onto the molecular weight distribution curve for the totalresulting polymer product, that curve will show two maxima or at leastbe distinctly broadened in comparison with the curves for the individualfractions. Such a polymer product is called bimodal. The chemicalcompositions of the two fractions may be different.

The term “chain extender” as used herein is a compound added to either apolyurethane or polyurea prepolymer, (or the prepolymer startingmaterials), which undergoes additional reaction but at a levelsufficiently low to maintain the thermoplastic properties of the finalcomposition

The term “conjugated” as used herein refers to an organic compoundcontaining two or more sites of unsaturation (e.g., carbon-carbon doublebonds, carbon-carbon triple bonds, and sites of unsaturation comprisingatoms other than carbon, such as nitrogen) separated by a single bond.

The term “curing agent” or “curing system” as used interchangeablyherein is a compound added to either polyurethane or polyureaprepolymer, (or the prepolymer starting materials), which impartsadditional crosslinking to the final composition to render it athermoset.

The term “(meth)acrylate” is intended to mean an ester of methacrylicacid and/or acrylic acid.

The term “(meth)acrylic acid copolymers” is intended to mean copolymersof methacrylic acid and/or acrylic acid.

The term “polyurea” as used herein refers to materials prepared byreaction of a diisocyanate with a polyamine.

The term “polyurethane” as used herein refers to materials prepared byreaction of a diisocyanate with a polyol.

The term “prepolymer” as used herein refers to any material that can befurther processed to form a final polymer material of a manufacturedgolf ball, such as, by way of example and not limitation, a polymerizedor partially polymerized material that can undergo additionalprocessing, such as crosslinking.

The term “thermoplastic” as used herein is defined as a material that iscapable of softening or melting when heated and of hardening again whencooled. Thermoplastic polymer chains often are not cross-linked or arelightly crosslinked using a chain extender, but the term “thermoplastic”as used herein may refer to materials that initially act asthermoplastics, such as during an initial extrusion process or injectionmolding process, but which also may be crosslinked, such as during acompression molding step to form a final structure.

The term “thermoplastic polyurea” as used herein refers to a materialprepared by reaction of a prepared by reaction of a diisocyanate with apolyamine, with optionally addition of a chain extender.

The “thermoplastic polyurethane” as used herein refers to a materialprepared by reaction of a diisocyanate with a polyol, with optionallyaddition of a chain extender.

The term “thermoset” as used herein is defined as a material thatcrosslinks or cures via interaction with as crosslinking or curingagent. The crosslinking may be brought about by energy in the form ofheat (generally above 200 degrees Celsius), through a chemical reaction(by reaction with a curing agent), or by irradiation. The resultingcomposition remains rigid when set, and does not soften with heating.Thermosets have this property because the long-chain polymer moleculescross-link with each other to give a rigid structure. A thermosetmaterial cannot be melted and re-molded after it is cured thusthermosets do not lend themselves to recycling unlike thermoplastics,which can be melted and re-molded.

The term “thermoset polyurethane” as used herein refers to a materialprepared by reaction of a diisocyanate with a polyol, and a curingagent.

The term “thermoset polyurea” as used herein refers to a materialprepared by reaction of a diisocyanate with a polyamine, and a curingagent.

The term “urethane prepolymer” as used herein is the reaction product ofdiisocyante and a polyol.

The term “urea prepolymer” as used herein is the reaction product of adiisocyanate and a polyamine.

The term “unimodal polymer” refers to a polymer comprising one mainfraction and more specifically to the form of the polymer's molecularweight distribution curve, i.e., the molecular weight distribution curvefor the total polymer product shows only a single maximum.

Materials

Polymeric materials generally considered useful for making the golf clubface cap according to the present invention include both synthetic ornatural polymers or blend thereof including without limitation,synthetic and natural rubbers, thermoset polymers such as otherthermoset polyurethanes or thermoset polyureas, as well as thermoplasticpolymers including thermoplastic elastomers such as metallocenecatalyzed polymer, unimodal ethylene/carboxylic acid copolymers,unimodal ethylene/carboxylic acid/carboxylate terpolymers, bimodalethylene/carboxylic acid copolymers, bimodal ethylene/carboxylicacid/carboxylate terpolymers, unimodal ionomers, bimodal ionomers,modified unimodal ionomers, modified bimodal ionomers, thermoplasticpolyurethanes, thermoplastic polyureas, polyamides, copolyamides,polyesters, copolyesters, polycarbonates, polyolefins, halogenated (e.g.chlorinated) polyolefins, halogenated polyalkylene compounds, such ashalogenated polyethylene [e.g. chlorinated polyethylene (CPE)],polyalkenamer, polyphenylene oxides, polyphenylene sulfides, diallylphthalate polymers, polyimides, polyvinyl chlorides, polyamide-ionomers,polyurethane-ionomers, polyvinyl alcohols, polyarylates, polyacrylates,polyphenylene ethers, impact-modified polyphenylene ethers,polystyrenes, high impact polystyrenes, acrylonitrile-butadiene-styrenecopolymers, styrene-acrylonitriles (SAN),acrylonitrile-styrene-acrylonitriles, styrene-maleic anhydride (S/MA)polymers, styrenic copolymers, functionalized styrenic copolymers,functionalized styrenic terpolymers, styrenic terpolymers, cellulosicpolymers, liquid crystal polymers (LCP), ethylene-propylene-dieneterpolymers (EPDM), ethylene-vinyl acetate copolymers (EVA),ethylene-propylene copolymers, ethylene vinyl acetates, polyureas, andpolysiloxanes and any and all combinations thereof.

One preferred family of polymers for making the golf club face cap ofthe present invention are the thermoplastic or thermoset polyurethanesand polyureas made by combination of a polyisocyanate and a polyol orpolyamine respectively. Any isocyanate available to one of ordinaryskill in the art is suitable for use in the present invention including,but not limited to, aliphatic, cycloaliphatic, aromatic aliphatic,aromatic, any derivatives thereof, and combinations of these compoundshaving two or more isocyanate (NCO) groups per molecule.

Any polyol available to one of ordinary skill in the polyurethane art issuitable for use according to the invention. Polyols suitable for useinclude, but are not limited to, polyester polyols, polyether polyols,polycarbonate polyols and polydiene polyols such as polybutadienepolyols.

Any polyamine available to one of ordinary skill in the polyurea art issuitable for use according to the invention. Polyamines suitable for useinclude, but are not limited to, amine-terminated hydrocarbons,amine-terminated polyethers, amine-terminated polyesters,amine-terminated polycaprolactones, amine-terminated polycarbonates,amine-terminated polyamides, and mixtures thereof.

The previously described diisocyante and polyol or polyamine componentsmay be previously combined to form a prepolymer prior to reaction withthe chain extender or curing agent. Any such prepolymer combination issuitable for use in the present invention. Commercially availableprepolymers include LFH580, LFH120, LFH710, LFH1570, LF930A, LF950A,LF601D, LF751D, LFG963A, LFG640D.

One preferred prepolymer is a toluene diisocyanate prepolymer withpolypropylene glycol. Such polypropylene glycol terminated toluenediisocyanate prepolymers are available from Uniroyal Chemical Company ofMiddlebury, Conn., under the trade name ADIPRENE® LFG963A and LFG640D.Most preferred prepolymers are the polytetramethylene ether glycolterminated toluene diisocyanate prepolymers including those availablefrom Uniroyal Chemical Company of Middlebury, Conn., under the tradename ADIPRENE® LF930A, LF950A, LF601D, and LF751D.

Polyol chain extenders or curing agents may be primary, secondary, ortertiary polyols. Diamines and other suitable polyamines may be added tothe compositions of the present invention to function as chain extendersor curing agents. These include primary, secondary and tertiary amineshaving two or more amines as functional groups.

Depending on their chemical structure, curing agents may be slow- orfast-reacting polyamines or polyols. As described in U.S. Pat. Nos.6,793,864, 6,719,646 and copending U.S. Patent Publication No.2004/0201133 A1, (the contents of all of which are hereby incorporatedherein by reference).

Suitable curatives for use in the present invention are selected fromthe slow-reacting polyamine group include, but are not limited to,3,5-dimethylthio-2,4-toluenediamine;3,5-dimethylthio-2,6-toluenediamine; N,N′-dialkyldiamino diphenylmethane; trimethylene-glycol-di-p-aminobenzoate;polytetramethyleneoxide-di-p-aminobenzoate, and mixtures thereof. Ofthese, 3,5-dimethylthio-2,4-toluenediamine and3,5-dimethylthio-2,6-toluenediamine are isomers and are sold under thetrade name ETHACURE® 300 by Ethyl Corporation. Trimethyleneglycol-di-p-aminobenzoate is sold under the trade name POLACURE 740M andpolytetramethyleneoxide-di-p-aminobenzoates are sold under the tradename POLAMINES by Polaroid Corporation. N,N′-dialkyldiamino diphenylmethane is sold under the trade name UNILINK® by UOP. Suitablefast-reacting curing agent can be used includediethyl-2,4-toluenediamine,4,4″-methylenebis-(3-chloro,2,6-diethyl)-aniline(available from Air Products and Chemicals Inc., of Allentown, Pa.,under the trade name LONZACURE®), 3,3′-dichlorobenzidene;3,3′-dichloro-4,4′-diaminodiphenyl methane (MOCA);N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine and Curalon L, atrade name for a mixture of aromatic diamines sold by Uniroyal, Inc. orany and all combinations thereof. A preferred fast-reacting curing agentis diethyl-2,4-toluene diamine, which has two commercial grades names,Ethacure® 100 and Ethacure® 100LC commercial grade has lower color andless by-product. Blends of fast and slow curing agents are especiallypreferred.

In another preferred embodiment the polyurethane or polyurea is preparedby combining a diisocyanate with either a polyamine or polyol or amixture thereof and one or more dicyandiamides. In a preferredembodiment the dicyandiamide is combined with a urethane or ureaprepolymer to form a reduced-yellowing polymer composition as describedin U.S. Patent Application No. 60/852,582 filed on Oct. 17, 2006, theentire contents of which are herein incorporated by reference in theirentirety. Another preferred family of polymers for making the golf clubface cap of the present invention are thermoplastic ionomer resins. Onefamily of such resins was developed in the mid-1960's, by E.I. DuPont deNemours and Co., and sold under the trademark SURLYN®. Preparation ofsuch ionomers is well known, for example see U.S. Pat. No. 3,264,272.Generally speaking, most commercial ionomers are unimodal and consist ofa polymer of a mono-olefin, e.g., an alkene, with an unsaturated mono-or dicarboxylic acids having 3 to 12 carbon atoms. An additional monomerin the form of a mono- or dicarboxylic acid ester may also beincorporated in the formulation as a so-called “softening comonomer”.The incorporated carboxylic acid groups are then neutralized by a basicmetal ion salt, to form the ionomer. The metal cations of the basicmetal ion salt used for neutralization include Li⁺, Na⁺, K⁺, Zn²⁺, Ca²⁺,Co²⁺, Ni²⁺, Cu²⁺, Pb²⁺, and Mg²⁺, with the Li⁺, Na⁺, Ca²⁺, Zn²⁺, andMg²⁺ being preferred. The basic metal ion salts include those derived byneutralization of for example formic acid, acetic acid, nitric acid, andcarbonic acid. The salts may also include hydrogen carbonate salts,metal oxides, metal hydroxides, and metal alkoxides.

Today, there are a wide variety of commercially available ionomer resinsbased both on copolymers of ethylene and (meth)acrylic acid orterpolymers of ethylene and (meth)acrylic acid and (meth)acrylate, allof which many of which are be used as a golf club component such as acover layer that provides a striking surface. The properties of theseionomer resins can vary widely due to variations in acid content,softening comonomer content, the degree of neutralization, and the typeof metal ion used in the neutralization. The full range commerciallyavailable typically includes ionomers of polymers of general formula,E/X/Y polymer, wherein E is ethylene, X is a C₃ to C₈ α,β ethylenicallyunsaturated carboxylic acid, such as acrylic or methacrylic acid, and ispresent in an amount from about 2 to about 30 weight % of the E/X/Ycopolymer, and Y is a softening comonomer selected from the groupconsisting of alkyl acrylate and alkyl methacrylate, such as methylacrylate or methyl methacrylate, and wherein the alkyl groups have from1-8 carbon atoms, Y is in the range of 0 to about 50 weight % of theE/X/Y copolymer, and wherein the acid groups present in said ionomericpolymer are partially neutralized with a metal selected from the groupconsisting of lithium, sodium, potassium, magnesium, calcium, barium,lead, tin, zinc or aluminum, and combinations thereof.

The ionomer may also be a so-called bimodal ionomer as described in U.S.Pat. No. 6,562,906 (the entire contents of which are herein incorporatedby reference). These ionomers are bimodal as they are prepared fromblends comprising polymers of different molecular weights In addition tothe unimodal and bimodal ionomers, also included are the so-called“modified ionomers” examples of which are described in U.S. Pat. Nos.6,100,321, 6,329,458 and 6,616,552 and U.S. Patent Publication U.S.2003/0158312 A1, the entire contents of all of which are hereinincorporated by reference. An example of such a modified ionomer polymeris DuPont® HPF-1000 available from E. I. DuPont de Nemours and Co. Inc.

Also useful for making the golf club face cap of the present inventionis a blend of an ionomer and a block copolymer. A preferred blockcopolymer is SEPTON HG-252. Such blends are described in more detail incommonly-assigned U.S. Pat. No. 6,861,474 and U.S. Patent PublicationNo. 2003/0224871 both of which are incorporated herein by reference intheir entireties.

In a further embodiment, the golf club face cap of the present inventioncan comprise a composition prepared by blending together at least threematerials, identified as Components A, B, and C, and melt-processingthese components to form in-situ, a polymer blend compositionincorporating a pseudo-crosslinked polymer network. Such blends aredescribed in more detail in commonly-assigned U.S. Pat. No. 6,930,150,to Kim et al., the content of which is incorporated by reference hereinin its entirety.

Component A is a monomer, oligomer, prepolymer or polymer thatincorporates at least five percent by weight of at least one type of anacidic functional group. Examples of such polymers suitable for use asinclude, but are not limited to, ethylene/(meth)acrylic acid copolymersand ethylene/(meth)acrylic acid/alkyl (meth)acrylate terpolymers, orethylene and/or propylene maleic anhydride copolymers and terpolymers.

As discussed above, Component B can be any monomer, oligomer, orpolymer, preferably having a lower weight percentage of anionicfunctional groups than that present in Component A in the weight rangesdiscussed above, and most preferably free of such functional groups.Preferred materials for use as Component B include polyester elastomersmarketed under the name PEBAX and LOTADER marketed by ATOFINA Chemicalsof Philadelphia, Pa.; HYTREL, FUSABOND, and NUCREL marketed by E.I.DuPont de Nemours & Co. of Wilmington, Del.; SKYPEL and SKYTHANE by S.K.Chemicals of Seoul, South Korea; SEPTON and HYBRAR marketed by KurarayCompany of Kurashiki, Japan; ESTHANE by Noveon; and KRATON marketed byKraton Polymers. A most preferred material for use as Component B isSEPTON HG-252. Component C is a base capable of neutralizing the acidicfunctional group of Component A and is a base having a metal cation.These metals are from groups IA, IB, IIA, IIB, IIIA, IIIB, IVA, IVB, VA,VB, VIA, VIB, VIIB and VIIIB of the periodic table. Examples of thesemetals include lithium, sodium, magnesium, aluminum, potassium, calcium,manganese, tungsten, titanium, iron, cobalt, nickel, hafnium, copper,zinc, barium, zirconium, and tin. Suitable metal compounds for use as asource of Component C are, for example, metal salts, preferably metalhydroxides, metal oxides, metal carbonates, or metal acetates. Thecomposition preferably is prepared by mixing the above materials intoeach other thoroughly, either by using a dispersive mixing mechanism, adistributive mixing mechanism, or a combination of these.

In a further embodiment, the golf club face cap of the present inventioncan comprise a polyamide. Specific examples of suitable polyamidesinclude polyamide 6; polyamide 11; polyamide 12; polyamide 4,6;polyamide 6,6; polyamide 6,9; polyamide 6,10; polyamide 6,12; polyamideMXD6; PA12, CX; PA12, IT; PPA; PA6, IT; and PA6/PPE.

The polyamide may be any homopolyamide or copolyamide. One example of agroup of suitable polyamides is thermoplastic polyamide elastomers.Thermoplastic polyamide elastomers typically are copolymers of apolyamide and polyester or polyether. For example, the thermoplasticpolyamide elastomer can contain a polyamide (Nylon 6, Nylon 66, Nylon11, Nylon 12 and the like) as a hard segment and a polyether orpolyester as a soft segment. In one specific example, the thermoplasticpolyamides are amorphous copolyamides based on polyamide (PA 12).Suitable amide block polyethers include those as disclosed in U.S. Pat.Nos. 4,331,786; 4,115,475; 4,195,015; 4,839,441; 4,864,014; 4,230,848and 4,332,920.

One type of polyetherester elastomer is the family of Pebax, which areavailable from Elf-Atochem Company. Preferably, the choice can be madefrom among Pebax 2533, 3533, 4033, 1205, 7033 and 7233. Blends orcombinations of Pebax 2533, 3533, 4033, 1205, 7033 and 7233 can also beprepared, as well. Some examples of suitable polyamides for use includethose commercially available under the trade names PEBAX, CRISTAMID andRILSAN marketed by Atofina Chemicals of Philadelphia, Pa., GRIVORY andGRILAMID marketed by EMS Chemie of Sumter, S.C., TROGAMID and VESTAMIDavailable from Degussa, and ZYTEL marketed by E.I. DuPont de Nemours &Co., of Wilmington, Del.

The polymeric compositions used to prepare the golf club face cap of thepresent invention also can incorporate one or more fillers. Such fillersare typically in a finely divided form, for example, in a size generallyless than about 20 mesh, preferably less than about 100 mesh U.S.standard size, except for fibers and flock, which are generallyelongated. Filler particle size will depend upon desired effect, cost,ease of addition, and dusting considerations. The appropriate amounts offiller required will vary depending on the application but typically canbe readily determined without undue experimentation.

The filler preferably is selected from the group consisting ofprecipitated hydrated silica, limestone, clay, talc, asbestos, barytes,glass fibers, aramid fibers, mica, calcium metasilicate, barium sulfate,zinc sulfide, lithopone, silicates, silicon carbide, diatomaceous earth,carbonates such as calcium or magnesium or barium carbonate, sulfatessuch as calcium or magnesium or barium sulfate, metals, includingtungsten, steel, copper, cobalt or iron, metal alloys, tungsten carbide,metal oxides, metal stearates, and other particulate carbonaceousmaterials, and any and all combinations thereof. Preferred examples offillers include metal oxides, such as zinc oxide and magnesium oxide. Inanother preferred embodiment the filler comprises a continuous ornon-continuous fiber. In another preferred embodiment the fillercomprises one or more so called nanofillers, as described in U.S. Pat.No. 6,794,447 and copending U.S. patent application Ser. No. 10/670,090filed on Sep. 24, 2003 and copending U.S. patent application Ser. No.10/926,509 filed on Aug. 25, 2004, the entire contents of each of whichare incorporated herein by reference.

Another particularly well-suited additive for use in the compositions ofthe present invention includes compounds having the general formula:(R₂N)_(m)—R′—(X(O)_(n)OR_(y))_(m),wherein R is hydrogen, or a C₁-C₂₀ aliphatic, cycloaliphatic or aromaticsystems; R′ is a bridging group comprising one or more C₁-C₂₀ straightchain or branched aliphatic or alicyclic groups, or substituted straightchain or branched aliphatic or alicyclic groups, or aromatic group, oran oligomer of up to 12 repeating units including, but not limited to,polypeptides derived from an amino acid sequence of up to 12 aminoacids; and X is C or S or P with the proviso that when X=C, n=1 and y=1and when X=S, n=2 and y=1, and when X=P, n=2 and y=2. Also, m=1-3. Thesematerials are more fully described in copending U.S. patent applicationSer. No. 11/182,170, filed on Jul. 14, 2005, the entire contents ofwhich are incorporated herein by reference. Most preferably the materialis selected from the group consisting of4,4′-methylene-bis-(cyclohexylamine)-carbamate (commercially availablefrom R.T. Vanderbilt Co., Norwalk Conn. under the tradename Diak®4),11-aminoundecanoicacid, 12-aminododecanoic acid, epsilon-caprolactam;omega-caprolactam, and any and all combinations thereof.

If desired, the various polymer compositions used to prepare the golfclub face cap of the present invention can additionally contain otherconventional additives such as, antioxidants, or any other additivesgenerally employed in plastics formulation. Agents provided to achievespecific functions, such as additives and stabilizers, can be present.Examplary suitable ingredients include plasticizers, pigments colorants,antioxidants, colorants, dispersants, U.V. absorbers, opticalbrighteners, mold releasing agents, processing aids, fillers, and anyand all combinations thereof. UV stabilizers, or photo stabilizers suchas substituted hydroxphenyl benzotriazoles may be utilized in thepresent invention to enhance the UV stability of the final compositions.An example of a commercially available UV stabilizer is the stabilizersold by Ciba Geigy Corporation under the tradename TINUVIN

Whereas the invention has been described in connection withrepresentative embodiments, it will be understood that the invention isnot limited to those embodiments. On the contrary, the invention isintended to encompass all modifications, alternatives, and equivalentsas may fall within the spirit and scope of the invention, as defined bythe appended claims.

1. A method for making a golf club head having a club head body and acomposite face plate, the method comprising: forming a lay-up ofmultiple prepreg plies, each prepreg ply comprising at least one layerof reinforcing fibers impregnated with a resin; at least partiallycuring the lay-up in a mold so as to form an at least partially curedlay-up having a bulge and roll; removing the at least partially curedlay-up from the mold; water-jet cutting the at least partially curedlay-up to form a composite part having specified dimensions and shapedfor use as a face plate or part of a face plate in a club head; andmounting the face plate to the club head body.
 2. The method of claim 1,wherein the lay-up, prior to cutting, has a central portion and asacrificial portion completely surrounding the central portion, and theact of water-jet cutting comprises water-jet cutting the sacrificialportion from the central portion, which forms the composite part.
 3. Themethod of claim 2, wherein the act of at least partially curing thelay-up leaves no more than one void in the central portion of thepartially cured lay-up.
 4. The method of claim 2, wherein the act of atleast partially curing the lay-up removes all voids from the centralportion of the partially cured lay-up.
 5. The method of claim 1, furthercomprising placing an outer layer on the composite part, the outer layerdefining a striking surface of the face plate.
 6. The method of claim 5,wherein the outer layer comprises a polymeric layer.
 7. The method ofclaim 5, wherein the outer layer comprises a metal layer.
 8. The methodof claim 7, wherein the metal layer is made of titanium, aluminum,magnesium, steel, or alloys thereof.
 9. The method of claim 1, whereinthe lay-up has a varying thickness.
 10. The method of claim 1, whereinthe resin comprises a thermoset resin.
 11. The method of claim 1,wherein the club head body defines a front opening and the face plate ismounted to the club head body so as to cover the front opening.
 12. Themethod of claim 1, wherein the lay-up has first and second opposingsurfaces and a thickness measured from the first surface to the secondsurface, and the act of water-jet cutting the at least partially curedlay-up forms an outer peripheral edge of the composite part that extendsfrom the first surface to the second surface.
 13. The method of claim 1,wherein the resin cross-links during curing.
 14. A method for making agolf club head having a club head body and a composite face plate, themethod comprising: forming a lay-up of multiple prepreg plies, eachprepreg ply comprising at least one layer of reinforcing fibersimpregnated with a resin, wherein at least a portion of the pliescomprise a plurality of elongated pre-preg strips arranged in acriss-cross pattern defining an overlapping region where the stripsoverlap each other, the lay-up having a first thickness at a locationspaced from the overlapping region and a second thickness at theoverlapping region, the second thickness being greater than the firstthickness at least partially curing the lay-up ; water-jet cutting theat least partially cured lay-up to form a composite part havingspecified dimensions and shaped for use as a face plate or part of aface plate in a club head; and mounting the face plate to the club headbody.
 15. The method of claim 14, wherein: the lay-up, prior to cutting,has a central portion and a sacrificial portion completely surroundingthe central portion, each prepreg strip extending continuously throughthe central portion and having opposite end portions extending into thesacrificial portion; and the act of water-jet cutting compriseswater-jet cutting the sacrificial portion from the central portion,which forms the composite part.
 16. A method for making a golf club headhaving a club head body and a composite face plate, the methodcomprising: forming a lay-up of multiple prepreg composite plies,wherein at least a portion of the plies comprise elongated stripsarranged in a criss-cross pattern defining one or more areas ofincreased thickness in the lay-up where one ore more of the stripsoverlap each other; at least partially curing the lay-up; trimming theat least partially cured lay-up by water-jet cutting to form a parthaving specified dimensions and shaped for use as a face plate or partof a face plate in a club head; and mounting the face plate to the clubhead body.
 17. The method of claim 16, wherein the part, after trimming,has a void content of about 1.7×10⁻⁶ percent or less by volume.
 18. Themethod of claim 16, wherein the part, after trimming, does not have anyvoids.
 19. The method of claim 16, wherein: the lay-up, prior totrimming, has a central portion and a sacrificial portion completelysurrounding the central portion, each strip extending continuouslythrough the central portion and having opposite end portions extendinginto the sacrificial portion; and the act of trimming comprises trimmingthe sacrificial portion from the central portion by water-jet cutting toform the part.
 20. The method of claim 16, further comprising placing anouter layer on a front surface of the part to form a striking face of aface plate.
 21. The method of claim 16, wherein the strips are arrangedwithin the lay-up to form a central projection of the lay-up having afirst thickness and a peripheral portion surrounding the projectionhaving a second thickness that is less than the first thickness.
 22. Themethod of claim 16, wherein strips are arranged within the lay-up toform an annular projection of the lay-up having a first thickness and arecessed portion of the lay-up surrounded by the projection, therecessed portion having a second thickness that is less than the firstthickness.
 23. The method of claim 16, wherein another portion of theplies comprise a plurality of oversized plies each having a centralportion and a peripheral sacrificial portion completely surrounding thecentral portion, and the act of trimming the at least partially curedlay-up comprises water-jet cutting the partially cured lay-up to removethe sacrificial portion from the central portion, which forms the part.24. The method of claim 23, wherein the oversized plies are arranged ingroups of oversized plies, and the strips are arranged in groups ofstrips that are interspersed between the groups of oversized plies.